Measurement of receiver sensitivity of a radio communication apparatus by radio and optical test signals

A radio communication apparatus (21) is tested by radio and optical test signals (RTS and OTS) simultaneously transmitted by a test transmitter (22). Each test signal carries a test digital data signal. The apparatus has a radio digital data recovering section (23-25) for recovering the test digital data signal as a first digital data signal from the radio test signal. An optical digital data recovering section (39-42, 44-46) recovers the test digital data signal as a second digital data signal from the optical test signal. A comparing section (48-52) produces a bit coincidence signal whenever corresponding bits between the first and the second digital data signals coincides with each other. A counter (54) counts up a count to an increased count in response to the bit coincidence signal during a predetermined time interval. An indicator (30-32) indicates the increased count as sensitivity of the apparatus.

BACKGROUND OF THE INVENTION 
This invention relates to a radio communication apparatus for use in 
combination with a test transmitter for testing the radio communication 
apparatus in order to measure a receiver sensitivity of the radio 
communication apparatus. This invention relates also to the test 
transmitter. The radio communication apparatus may be a radio paging 
receiver, a transceiver, or the like although description will be mainly 
directed to the radio paging receiver. 
A radio paging receiver of the type described, is for receiving a radio 
communication signal which carries a communication digital data signal. 
The radio paging receiver generally comprises a radio digital data 
recovering section for recovering the communication digital data signal 
from the radio communication signal. Connected to the radio digital data 
recovering section, a data processing section processes the communication 
digital data signal into a processed data signal. Connected to the data 
processing section, an announcing section carries out an announcing 
operation of producing an announcement to an attendant to the radio paging 
receiver in response to the processed data signal. 
A test transmitter of the type described, generally comprises a test signal 
generator for generating a test digital data signal. Connected to the test 
signal generator, a radio test signal transmitting section transmits the 
radio test signal which carries the test digital data signal. 
On using the test transmitter in testing the radio paging receiver so as to 
measure a receiver sensitivity of the radio paging receiver in relation to 
the communication digital data signal, the test digital data signal is 
made to represent an identification number specific to the radio paging 
receiver. 
When the radio test signal has a high electric field strength, the radio 
paging receiver can correctly receive the test digital data signal with 
the test digital data signal subjected to no bit error. In this case, the 
radio digital data recovering section correctly recovers the test digital 
data signal from the radio test signal in the radio paging receiver. The 
data processing section processes the test digital data signal into the 
processed data signal. The announcing section duly carries out the 
announcing operation. 
When the radio test signal has a low electric field strength, the radio 
paging receiver may receive the test digital data signal with the test 
digital data signal subjected to bit errors. Inasmuch as the radio paging 
receiver can not correctly receive the test digital data signal in this 
case, the data processing section does not produce the processed data 
signal. The announcing section does not carry out the announcing 
operation. 
Conventionally, the receiver sensitivity of the radio paging receiver is 
defined as a lowest electric field strength in which the radio paging 
receiver can carry out the announcing operation. Inasmuch as the receiver 
sensitivity (that is, the lowest electric field strength of the radio test 
signal) is determined by judging whether or not the radio paging receiver 
carries out the announcing operation, it is necessary to make the test 
signal generator of the test transmitter generate the test digital data 
signal which represents the identification number specific to the radio 
paging receiver. When a different radio paging receiver is tested, it is 
necessary to make the test signal generator generate the test digital data 
signal which represents a different identification number specific to the 
different radio paging receiver. This results in an increase in labor and 
time of measurement of the receiver sensitivity in proportion to an 
increase in the number of the radio paging receivers. 
Furthermore, it is difficult to quantitatively know the number of either 
correct bits or erroneous bits in the test digital data signal carried by 
the radio test signal which the radio paging receiver receives when the 
radio test signal has a particular electric field strength between the 
high electric field strength and the low electric field strength. 
SUMMARY OF THE INVENTION 
It is therefore an object of this invention to provide a radio 
communication apparatus operable in combination with a test transmitter, 
which apparatus is capable of quantitatively measuring, as a receiver 
sensitivity of the radio communication apparatus, the number of correct or 
nonerroneous bits in a test digital data signal carried by a radio test 
signal which the radio communication apparatus receives when the radio 
test signal has a particular electric field strength. 
It is another object of this invention to provide a radio communication 
apparatus of the type described, wherein it is unnecessary to make a test 
signal generator of the test transmitter generate the test digital data 
signal which represents an identification number specific to the radio 
communication apparatus. 
It is still another object of this invention to provide a radio 
communication apparatus of the type described, wherein it is possible to 
decrease labor and time of measurement of the receiver sensitivity of the 
radio communication apparatus. 
It is a further object of this invention to provide a test transmitter for 
use in combination with a radio communication apparatus, which test 
transmitter is capable of quantitatively measuring, as a receiver 
sensitivity of the radio communication apparatus, the number of correct 
bits in a test digital data signal carried by a radio test signal which 
the radio communication apparatus receives when the radio test signal has 
a particular electric field strength. 
It is a still further object of this invention to provide a test 
transmitter of the type described, wherein it is unnecessary to make a 
test signal generator of the test transmitter generate the test digital 
data signal which represents an identification number specific to the 
radio communication apparatus. 
It is a yet further object of this invention to provide a test transmitter 
of the type described, wherein it is possible to decrease labor and time 
of measurement of the receiver sensitivity of the radio communication 
apparatus. 
Other objects of this invention will become clear as the description 
proceeds. 
On describing the gist of an aspect of this invention, it is possible to 
understand that a radio communication apparatus is for receiving a radio 
communication signal carrying a communication digital data signal and a 
radio test signal carrying a test digital data signal. The radio 
communication apparatus includes radio digital data recovering means for 
recovering the communication digital data signal from the radio 
communication signal and the test digital data signal as a first digital 
data signal from the radio test signal. 
According to this aspect of this invention, the above-understood radio 
communication apparatus is for receiving an optical test signal carrying 
the test digital data signal. The radio communication apparatus comprises 
optical digital data recovering means for recovering the test digital data 
signal as a second digital data signal from the optical test signal, 
timing pulse generating means connected to the optical digital data 
recovering means for generating a timing pulse signal in bit synchronism 
with the second digital data signal, comparing means connected to the 
radio and the optical digital data recovering means for comparing the 
first digital data signal with the second digital data signal bit by bit 
to successively produce bit coincidence pulses whenever the first and the 
second digital data signals are coincident with each other bit by bit, a 
first counter connected to the timing pulse generating means for counting 
up a first count in response to the timing pulse signal from an initial 
value to a predetermined threshold value to produce a count stop signal 
when the first count is counted up to the threshold value, and a second 
counter connected to the comparing means and the first counter for 
counting up a second count in response to the bit coincidence pulses from 
an initial count to an increased count until production of the count stop 
signal to produce a count signal which represents the increased count as a 
receiver sensitivity of the radio communication apparatus in relation to 
the communication digital data signal. 
On describing the gist of a specific aspect of this invention, it is 
possible to understand that a radio communication apparatus is for 
receiving a radio communication signal carrying a communication digital 
data signal. The radio communication apparatus is for use in combination 
with a test transmitter including a test signal generator for generating a 
test digital data signal, and radio test signal transmitting means 
connected to the test signal generator for transmitting a radio test 
signal carrying the test digital data signal. The radio communication 
apparatus includes radio digital data recovering means for recovering the 
communication digital data signal from the radio communication signal and 
the test digital data signal as a receiver recovered digital data signal 
from the radio test signal. 
According to the specific aspect of this invention, the above-understood 
radio communication apparatus comprises optical test signal transmitting 
means connected to the radio digital data recovering means for 
transmitting an optical test signal carrying the receiver recovered 
digital data signal. The test transmitter comprises optical digital data 
recovering means for recovering the receiver recovered digital data signal 
as a transmitter recovered digital data signal from the optical test 
signal, timing pulse generating means connected to the test signal 
generator for generating a timing pulse signal in bit synchronism with the 
test digital data signal, comparing means connected to the test signal 
generator and the optical data recovering means for comparing the 
transmitter recovered digital data signal with the test digital data 
signal to successively produce bit coincidence pulses whenever the test 
digital data signal and the transmitter recovered digital data signal are 
coincident with each other bit by bit, a first counter connected to the 
timing pulse generating means for counting up a first count in response to 
the timing pulse signal from an initial value to a predetermined threshold 
value to produce a count stop signal when the first count is counted up to 
the threshold value, and a second counter connected to the comparing means 
and the first counter for counting up a second count in response to the 
bit coincidence pulses from an initial count to an increased count until 
production of the count stop signal to produce a count signal which 
represents the increased count as a receiver sensitivity of the radio 
communication apparatus in relation to the communication digital data 
signal. 
On describing the gist of a different aspect of this invention, it is 
possible to understand that a test transmitter for use in testing radio 
communication apparatus for receiving a radio communication signal 
carrying a communication digital data signal. The test transmitter 
includes a test signal generator for generating a test digital data 
signal, and radio test signal transmitting means connected to the test 
signal generator for transmitting a radio test signal carrying the test 
digital data signal. The radio communication apparatus includes radio 
digital data recovering means for recovering the communication digital 
data signal from the radio communication signal and the test digital data 
signal as a receiver recovered digital data signal from the radio test 
signal. 
According to the different aspect of this invention, the above-understood 
test transmitter comprises optical digital data recovering means for 
recovering the receiver recovered digital data signal as a transmitter 
recovered digital data signal from an optical test signal carrying the 
receiver recovered digital data signal, the optical test signal being 
transmitted by optical test signal transmitting means which is connected 
to the radio digital data recovering means in the radio communication 
apparatus, timing pulse generating means connected to the test signal 
generator for generating a timing pulse signal in bit synchronism with the 
test digital data signal, comparing means connected to the test signal 
generator and the optical data recovering means for comparing the 
transmitter recovered digital data signal with the test digital data 
signal to successively produce bit coincidence pulses whenever the test 
digital data signal and the transmitter received digital data signal are 
coincident with each other bit by bit, a first counter connected to the 
timing pulse generating means for counting up a first count in response to 
the timing pulse signal from an initial value to a predetermined threshold 
value to produce a count stop signal when the first count is counted up to 
the threshold value, and a second counter connected to the comparing means 
and the first counter for counting up a second count in response to the 
bit coincidence pulses from an initial count to an increased count until 
production of the count stop signal to produce a count signal which 
represents the increased count as a receiver sensitivity of the radio 
communication apparatus in relation to the communication digital data 
signal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, a radio paging system comprises a base station 20, a 
radio paging receiver 21 according to a first embodiment of this 
invention, and other radio paging receivers (not shown) which are similar 
in structure and in operation to the radio paging receiver 21. The base 
station 20 is for transmitting a radio communication signal indicated at 
RCS. The radio paging receiver 21 receives and deals with the radio 
communication signal RCS. The radio paging receiver 21 is for use in 
combination with a test transmitter 22 which will later be described. 
Turning to FIG. 2, the radio communication signal RCS is illustrated. The 
illustrated radio communication signal RCS is a POGSAG code radio signal 
which is set up in CCIR recommendation 584. The radio communication signal 
RCS comprises a plurality of frames which are similar in frame structure 
to one another. 
Each frame of the radio communication signal RCS carries a synchronization 
signal SYN and first through q-th subframes SF1 to SFq successively 
succeeding the synchronization signal SYN, where q represents a positive 
integer. The synchronization signal SYN has a predetermined number of bits 
and is specified by a predetermined pattern of bits. 
The radio paging receiver 21 (FIG. 1) and other radio paging receivers of 
the radio paging system have identification or call numbers different from 
one another and may be grouped into first through q-th groups. The first 
through the q-th groups are assigned to the first through the q-th 
subframes SF1 to SFq of each frame, respectively. Supposing that the radio 
paging receiver 21 belongs to the first group, the base station 20 (FIG. 
1) transmits a call number signal CN representative of the identification 
or call number specific to the radio paging receiver 21 and a 
communication message signal CME representative of a communication message 
directed to the radio paging receiver 21 by using the first subframe SF1. 
The call number signal CN has first through P-th bits, where P represents 
a natural number greater than one. The communication message signal CME 
has a preselected number of bits. Each of the synchronization signal SYN, 
the call number signal CN, and the communication message signal CME 
consists of Bose-Chaudhuri-Hocquenghem (BCH) codes. 
A combination of the synchronization signal SYN, the call number signal CN, 
and the communication message signal CME will be referred to herein as a 
communication digital data signal. The communication digital data signal 
is carried by the radio communication signal RCS. 
Turning back to FIG. 1 with reference to FIG. 2 continued, description will 
be made as regards operation of the radio paging receiver 21 when the 
paging receiver 21 receives the radio communication signal RCS. The radio 
communication signal RCS is picked up by an antenna 23 and supplied to a 
radio section 24. The radio section 24 converts or demodulates the radio 
communication signal RCS into a baseband or demodulated signal. Connected 
to the radio section 24, a first waveform shaper 25 shapes the demodulated 
signal into a shaped signal of a digital waveform. The shaped signal has 
the communication digital data signal (namely, a combination of the 
synchronization signal SYN, the call number signal CN, and the 
communication message signal CME). 
Thus, a combination of the antenna 23, the radio section 24, and the first 
waveform shaper 25 serves as a radio digital data recovering section. The 
radio digital data recovering section (23, 24, 25) is for recovering the 
communication digital data signal from the radio communication signal RCS. 
A decoder 26 is supplied with the communication digital data signal and 
detects the synchronization signal SYN in order to establish bit 
synchronization and frame synchronization. After the bit synchronization 
and frame synchronization are established, the decoder 26 cooperates with 
a P-ROM (programmable read-only memory) 27 which preliminarily memorizes 
first through P-th bits of a directory number signal representative of the 
identification number specific to the radio paging receiver 21. That is, 
the decoder 26 compares the call number signal CN with the directory 
number signal bit by bit. 
When the decoder 26 detects coincidence between the bits of the call number 
signal CN with the directory number signal, the decoder 26 sends a speaker 
drive signal to a loudspeaker 28 through a speaker driver 29 to make the 
loudspeaker 28 generate a call tone indicative of a call to the radio 
paging receiver 21 a predetermined time duration. Simultaneously, the 
decoder 26 sends the communication message signal CME to a signal 
processor 30. Responsive to the communication message signal CME, the 
signal processor 30 makes the display unit 31 visually display the 
communication message of the communication message signal CME through a 
display driver 32. The display unit 31 is, for example, a liquid crystal 
display (LCD). 
Thus, the decoder 26 serves, in cooperation with the P-ROM 27, the speaker 
driver 29, the signal processor 30, and the display driver 32 as a data 
processing section connected to the radio digital data recovering section 
(23, 24, 25). The data processing section (26, 27, 29, 30, 32) processes 
the communication digital data signal into a processed signal (namely, the 
speaker drive signal and the communication message signal CME). A 
combination of the loudspeaker 28 and the display unit 31 serves as an 
announcing section connected to the data processing section (26, 27, 29, 
30, 32). The announcing section (28, 29) carries out an announcing 
operation of production of the processed data signal in response to the 
processed data signal. 
Turning to FIG. 3 with reference to FIG. 1 continued, description will 
proceed to the test transmitter 22. The test transmitter 22 is for use in 
testing the radio paging receiver 21. The test transmitter 22 is usually 
carried by a maintenance engineer who is in charge of maintenance service 
of the radio paging system. The test transmitter 22 is for transmitting a 
radio test signal which is indicated at RTS and which carries a test 
digital data signal. The test transmitter 22 is furthermore for 
transmitting an optical test signal indicated at OTS. The optical test 
signal OTS carries the test digital data signal like the radio test signal 
RTS. 
The test transmitter 22 has an encoder 33 which generates the test digital 
data signal having logic "1" and "0" levels. More specifically, the test 
digital data signal successively comprises first through N-th bits, where 
N represents a first integer which is greater than one. 
The test digital data signal is illustrated in FIG. 3 along a first or top 
line. The illustrated test digital data signal successively comprises 
logic "0", "1", "1", "0", "0", "1", and "0" levels. 
In FIG. 1, the encoder 33 simultaneously supplies the test digital data 
signal to a radio test signal producer 34 and to an emitter driver 35 for 
driving a light emitter 36 which is, for example, an LED (light-emitting 
diode), a laser diode, or the like. 
When supplied with the test digital data signal, the radio test signal 
producer 34 produces the radio test signal RTS carrying the test digital 
data signal. The radio test signal RTS is transmitted through an 
attenuator 37 and an antenna 38. 
When supplied with the test digital data signal, the emitter driver 35 
produces an on-off drive signal which indicates on and off when the test 
digital data signal has logic "1" and "0" levels, respectively. Responsive 
to the on-off drive signal, the light emitter 36 emits or transmits a 
flicker light which indicates logic "1" and "0" levels of the test digital 
data signal as the optical test signal OTS carrying the test digital data 
signal. More specifically, the optical test signal OTS is controlled or 
modulated by the test digital data signal to form the flicker light which 
indicates logic "1" and "0" levels of the test digital data signal. 
With reference to FIGS. 1 and 3 continued, description will be made as 
regards operation of the radio paging receiver 21 when the radio paging 
receiver 21 is tested by the test transmitter 22. In this event, the 
maintenance engineer puts a switch 39 in an on state and makes the test 
transmitter 22 transmit the radio and the optical test signals RTS and 
OTS. 
The radio test signal RTS is picked up by the antenna 23 and supplied to 
the radio section 24. The radio section 24 converts or demodulates the 
radio test signal RTS into a baseband or demodulated signal. The 
demodulated signal is illustrated in FIG. 3 along a second line. The 
illustrated demodulated signal is demodulated by the radio section 24 when 
the radio test signal RTS has a high electric field strength. 
In FIG. 1, the first waveform shaper 25 shapes the demodulated signal into 
a first shaped signal of a digital waveform by comparing the demodulated 
signal with a predetermined threshold level illustrated in FIG. 3 along 
the second line. The first shaped signal will be referred to as a first 
digital data signal and is illustrated in FIG. 3 along a third line. The 
first digital data signal has a high level when the demodulated signal has 
an amplitude larger than the threshold level. When the demodulated signal 
has another amplitude which is not larger than the threshold level, the 
first digital data signal has a low level. The illustrated first digital 
data signal is equivalent in waveform to the test digital data signal 
produced by the encoder 33. That is, the radio paging receiver 21 
correctly receives the test digital data signal with the test digital data 
signal subjected to no bit error. However, a time difference or delay 
between the test digital data signal and the first digital data signal 
inevitably produces due to a circuit delay of the radio section 24, the 
first waveform shaper 25, and so on. 
As illustrated in FIG. 3 along a fourth line, the demodulated signal is 
demodulated by the radio section 24 when the radio test signal RTS has a 
low electric field strength. In this case, the first waveform shaper 25 
produces the first digital data signal illustrated in FIG. 3 along the 
fifth line. The illustrated first digital data signal successively 
comprises logic "0", "1", "1", "0", "1", "1", and "0" levels. That is, the 
radio paging receiver 21 receives the test digital data signal with the 
test digital data signal subjected to a bit error. In the illustrated 
example, the bit error occurs at a fifth bit of the first digital data 
signal. 
Thus, the radio digital data recovering section (23, 24, 25) is furthermore 
for recovering the test digital data signal as the first digital data 
signal from the radio test signal RTS. 
A photoelectric converter 40 converts the optical test signal OTS into a 
converted or demodulated signal. Connected to the photoelectric converter 
40, a second waveform shaper 41 shapes the converted signal into a second 
shaped signal of digital waveform that is equivalent to the test digital 
data signal. Inasmuch as the optical test signal OTS has no relation to 
the electric field strength, the optical test signal OTS can be received 
with the test digital data signal subjected to no bit error. The second 
shaped signal has a waveform substantially equivalent to the shaped signal 
illustrated in FIG. 3 along the third line. 
In FIG. 1, the switch 39 has negative and positive terminals connected to 
the earth or ground directly and a voltage source through a resistor 42, 
respectively. The voltage source is indicated at +V and gives a positive 
voltage to the positive terminal. The negative terminal is supplied with 
an earth voltage. It will be assumed that the positive and the earth 
voltages corresponding to a logic "1" level and a logic "0" level. 
The switch 39 is usually put in an off state. That is, the switch 39 is put 
in the off state when the radio and the optical test signals RTS and OTS 
are not transmitted by the test transmitter 22. In this case, a first AND 
circuit 43 is supplied with the logic "1" level through the resistor 42. 
Inasmuch as an inverter 44 is supplied with the logic "1" level through 
the resistor 42 and inverts the logic "1" level into the logic "0" level, 
a second AND circuit 45 is supplied with the logic "0" level. The first 
AND circuit 43 thereby delivers to the signal processor 30 an output 
signal of the second waveform shaper 41. In this event, the signal 
processor 30 operates in the manner which will later be described. 
Turning to FIG. 4 with reference to FIG. 1 continued, description will 
proceed to a case where the switch 39 is put in the on state. As mentioned 
above, the switch 39 is put in the on state by the maintenance engineer 
when the radio paging receiver 21 is tested by the test transmitter 22. In 
this case, the earth voltage (namely, the logic "0" level) is supplied to 
the inverter 44 through the switch 39. Inasmuch as the inverter 44 
supplies the second AND circuit 45 with the logic "1" level, the second 
AND circuit 45 supplies a delay circuit 46 with the second shaped signal 
produced by the second waveform shaper 41. The delay circuit 46 gives the 
second shaped signal of the second waveform shaper 41 a predetermined 
delay so that the first bit of the shaped signal of the second waveform 
shaper 41 coincides with the first bit of the first digital data signal 
produced by the first waveform shaper 25. The delay circuit 46 thereby 
produces a delayed signal which will be referred to as a second digital 
data signal. 
Thus, a combination of the photoelectric converter 40, the second waveform 
shaper 41, the switch 39, the voltage source +V, the resistor 42, the 
inverter 44, the second AND circuit 45, and the delay circuit 46 is 
operable as an optical digital data recovering section. The optical 
digital data recovering section (39-42, +V, 44-46) recovers the test 
digital data signal as the second digital data signal from the optical 
test signal OTS. 
In FIG. 4, the test digital data signal produced by the encoder 33 is 
illustrated along a first line. First through seventh bits of the 
illustrated test digital data signal have the logic "0", "1", "1", "0", 
"0", "1", and "0" levels, respectively. 
As illustrated in FIG. 4 along a second line, the second digital data 
signal produced by the delay circuit 46 of the optical digital data 
recovering section has a waveform which is substantially equivalent to the 
test digital data signal. This is because the optical test signal OTS can 
be received with the test digital data signal subjected to no bit error as 
mentioned above. 
The first digital data signal produced by the first waveform shaper 25 of 
the radio digital data recovering section (23, 24, 25) is illustrated in 
FIG. 4 along a third line. The illustrated first digital data signal is 
equivalent to the first digital data signal illustrated in FIG. 3 along 
the fifth line and has the bit error which occurs at the fifth bit of the 
first digital data signal as mentioned above. 
In FIG. 1, a timing pulse generator 47 is connected to the delay circuit 46 
of the optical digital data recovering section (39-42, +V, 44-46). The 
timing pulse generator 47 generates a timing pulse signal in bit 
synchronism with the second digital data signal. More specifically, the 
timing pulse generator 47 successively generates first through N-th timing 
pulses collectively as the timing pulse signal in bit synchronism with the 
first through the N-th bits of the second digital data signal. The timing 
pulse signal is illustrated in FIG. 4 along a fifth line. 
In FIGS. 1 and 4, a third AND circuit 48 is directly connected to the first 
waveform shaper 25, the delay circuit 46, and the timing pulse generator 
47. The third AND circuit 48 successively produces first coincidence 
pulses whenever n-th bits of the first and the second digital data signals 
and an n-th timing pulse are coincident with one another, where n 
consecutively varies from 1 to N. In this event, each of the first 
coincidence pulses is produced when the n-th bit of the first digital data 
signal and the n-th bit of the second digital data signal have the logic 
"1" level in common. 
Connected to the first waveform shaper 25 and the delay circuit 46 through 
inverters 49 and 50, respectively, and connected to the timing pulse 
generator 47 directly, a fourth AND circuit 51 successively produces 
second coincidence pulses whenever inverted bits of the n-th bits of the 
first and the second digital data signals and the n-th timing pulse are 
coincident with one another. In this event, each of the second coincidence 
pulses is produced when the n-th bit of the first digital data signal and 
the n-th bit of the second digital data signal have the logic "0" level in 
common. 
Connected to the third and the fourth AND circuits 48 and 51, an OR circuit 
52 produces the first and the second coincidence pulses as bit coincidence 
pulses. In FIG. 4, the bit coincidence pulses are illustrated along a 
fifth line. 
Thus, a combination of the third and the fourth AND circuits 48 and 51, the 
inverters 49 and 50, and the OR circuit 52 serves as a comparing section 
connected to the radio digital data recovering section (23, 24, 25) and 
the optical digital data recovering section (39-42, 44, 45, +V). The 
comparing section (48-52) compares the first digital data signal with the 
second digital data signal bit by bit and successively produces the bit 
coincidence pulses whenever the first and the second digital data signals 
are coincident with each other bit by bit. More specifically, the 
comparing section (48-52) compares the first through the N-th bits of the 
first digital data signal with the first through the N-th bits of the 
second digital data signal, respectively, and successively produces the 
bit coincidence pulses whenever n-th bits of the first and the second 
digital data signals are coincident with each other, where n consecutively 
varies from 1 to N. 
In FIG. 1, a first counter 53 is connected to the timing pulse generator 
47. The first counter 53 counts up a first count in response to the timing 
pulse signal from an initial value to a predetermined threshold value and 
produces a count stop signal when the first count is counted up to the 
threshold value. The threshold value is greater than the initial value by 
a second integer M which is greater than one and is not greater than the 
first integer N. More specifically, the first counter 53 counts up the 
first count to at least a part of the first through the N-th timing pulses 
and produces the count stop signal when the first count increases up to 
the threshold value. 
Connected to the OR circuit 52 of the comparing section (48-52) and the 
first counter 53, a second counter 54 counts up a second count in response 
to the bit coincidence pulses from an initial count equal to zero to an 
increased count until production of the count stop signal and produces a 
count signal which represents the increased count as a receiver 
sensitivity of the radio paging receiver 21 in relation to the 
communication digital data signal. More specifically, the second counter 
54 counts up the second count in response to the bit coincidence pulses 
which are produced when n consecutively varies from 1 towards N. The 
second counter 54 produces the count signal. 
Connected to the second counter 54, the signal processor 30 makes the 
display unit 31 display, as the receiver sensitivity of the radio paging 
receiver 21, the increased count of the count signal through the display 
driver 32. Supposing that the second integer M is equal to 100, the 
display unit 31 displays the number of bit coincidence pulses produced 
during a time duration corresponding to 100 timing pulses. In this case, 
the display unit 31 displays percentage of the number of correct or 
nonerroneous bits in the test digital data signal carried by the radio 
test signal RTS which the radio paging receiver 21 receives when the radio 
test signal RTS has a particular electric field strength. 
Thus, a combination of the signal processor, the display driver 32, and the 
display unit 31 is operable as an indicating section connected to the 
second counter 54. The indicating section (30, 31, 32) indicates, as the 
receiver sensitivity of the radio paging receiver 21, the increased count 
represented by the count signal. 
In FIG. 1, the radio paging receiver 21 further comprises an illuminator 
55, such as a lamp, connected to the signal processor 30 through an 
illuminator driver 56. The illuminator 55 illuminates the display unit 31 
by illuminating light when the illuminator 55 is driven by the signal 
processor 30. As mentioned above, the signal processor 30 is supplied with 
the output signal of the second waveform shaper 41 through the AND circuit 
43 when the switch 39 is put in the off state. Inasmuch as the maintenance 
engineer does not make the test transmitter 22 transmit the optical test 
signal OTS when the switch 39 is put in the off state, the photoelectric 
converter 40 is not supplied with the optical test signal OTS but supplied 
with environment light of the paging receiver 21. When the environment 
light has a low intensity or brightness, the output signal of the second 
waveform shaper 41 has a logic "1" level. When the environment light has a 
high intensity or brightness, the output signal of the second waveform 
shaper 41 has a logic "0" level. That is, when environment of the radio 
paging receiver 21 becomes dark, the output signal of the second waveform 
shaper 41 has a logic "1" level. On condition that the signal processor 30 
receives the output signal of the logic "1" level from the second waveform 
shaper 41 through the first AND circuit 43 (namely, the environment of the 
radio paging receiver 21 becomes dark) when the signal processor 30 drives 
the display unit 31 so as to make the display unit 31 display the 
communication message CME (FIG. 2) recovered by the decoder 26, the signal 
processor 30 drives the illuminator 55 to make the illuminator 55 
illuminate the display unit 31 by the illuminating light. 
Turning to FIG. 5, description will proceed to a radio paging receiver 60 
according to a second embodiment of this invention. The radio paging 
receiver 60 comprises similar parts designated by like reference numerals. 
The radio paging receiver comprises a mode selector 61 which selects a 
normal and a test mode of operation. The normal and the test mode are 
indicated at N and T, respectively. First through third selectors 62, 63, 
and 64 are connected to the mode selector 61. Each of the first through 
the third selectors 62 to 64 selects a normal mode N of operation when the 
mode selector 61 selects the normal mode N. When the mode selector 61 
selects the test mode T, each of the first through the third selectors 62 
to 64 selects a test mode T of operation. 
A combination of the mode selector 61 and the first through the third 
selectors 62 to 64 will be referred to as a mode selecting section for 
selecting the normal and the test mode of operation. 
It will be assumed that the maintenance engineer makes the mode selector 61 
select the test mode T and that the test transmitter 22 transmits the 
radio and the optical test signals RTS and OTS. In this case, the first 
through the third selectors 62 to 64 selects the test mode T. 
In the test mode T, the timing pulse generator 47 is connected to the 
second waveform shaper 41 of the optical digital data recovering section 
(40, 41) through the first selector 62 of the mode selecting section 
(61-64). As a result, the timing pulse generator 47 successively generates 
the first through the N-th timing pulses in bit synchronism with the first 
through the N-th bits of the second digital data signal recovered by the 
second waveform shaper 41 of the optical digital data recovering section 
(40, 41). 
A comparing section 65 is connected to the first waveform shaper 25 of the 
radio digital data recovering section (23-25) directly and to the timing 
pulse generator 47 directly. The comparing section 65 is furthermore 
connected to the second waveform shaper 41 of the optical digital data 
recovering section (40, 41) through the second selector 63 of the mode 
selecting section (61-64) in the test mode T. Like the comparing section 
(48-52) of the radio paging receiver 21 of FIG. 1, the comparing section 
65 compares, in the test mode T, the first through the N-th bits of the 
first digital data signal from the first waveform shaper 25 with the first 
through the N-th bits of the second digital data signal from the second 
waveform shaper 41, respectively, and successively produces the bit 
coincidence pulses whenever the n-th bits of the first and the second 
digital data signals are coincident with each other, where n consecutively 
varies from 1 to N. 
The second counter 54 is connected to the comparing section 65 through the 
third selector 64 of the mode selecting section (61-64) in the test mode 
T. Like in the radio paging receiver 21, the second counter 54 counts up 
the second count until production of the count stop signal from the first 
counter 53 in response to the bit coincidence pulses which are produced 
when n consecutively varies from 1 to N. The second counter 54 produces 
the count signal which represents the increased count as a receiver 
sensitivity of the radio paging receiver 60. 
Connected to the mode selector 61 and responsive to the count signal, the 
signal processor 30 makes the display unit 31 display the increased count 
of the count signal as the receiver sensitivity of the radio paging 
receiver 60 in the test mode T. 
It will be assumed that the mode selector 61 selects the normal mode N and 
that the radio paging receiver 60 receives the radio communication signal 
RCS instead of the radio and the optical test signals RTS and OTS. In this 
case, the first through the third selectors 62 to 64 selects the normal 
mode N. 
As mentioned above, the communication digital data signal is carried by the 
radio communication signal RCS and comprises the call number signal CN 
(FIG. 2) having the first through the P-th bits. 
The P-ROM 27 produces a specific digital data signal successively 
comprising first through P-th bits in synchronism with the first through 
the P-th bits of the communication digital data signal. The first through 
the P-th bits of the specific digital data signal collectively represents 
the identification number specific to the radio paging receiver 60. 
In the normal mode N, the timing pulse generator 47 is connected to the 
first waveform shaper 25 of the radio digital data recovering section 
(23-25) through the first selector 62 of the mode selecting section 
(61-64) and to the P-ROM 27 through a signal supply lead 66. As a result, 
the timing pulse generator 47 successively generates first through P-th 
timing pulses in bit synchronism with the first through the P-th bits of 
the communication digital data signal recovered by the first waveform 
shaper 25 of the radio digital data recovering section (23-25). 
The comparing section 65 is connected to the P-ROM 27 through the second 
selector 63 of the mode selecting section (61-64) and is connected to the 
first waveform shaper 25 of the radio digital data recovering section 
(23-25) directly and to the timing pulse generator 47 directly. In the 
manner similar to operation of the comparing section 65 in the test mode 
T, the comparing section 65 compares, in the normal mode N, the first 
through the P-th bits of the communication digital data signal from the 
first waveform shaper 25 with the first through the P-th bits of the 
specific digital data signal from the P-ROM 27, respectively, and 
successively produces output coincidence pulses whenever p-th bits of the 
communication and the specific digital data signals are coincident with 
each other, where p consecutively varies from 1 to p. 
More specifically, the P-ROM 27 memorizes first through P-th bits of a 
directory number signal representative of the identification number 
specific to the radio paging receiver 60 like in the radio paging receiver 
21 of FIG. 1. The signal supply lead 66 is connected to the timing pulse 
generator 47 and to the P-ROM 27 for supplying the first through the P-th 
timing pulses to the P-ROM 27 to make the P-ROM 27 produce the first 
through the P-th bits of the directory number signal in bit synchronism 
with the first through the P-th timing pulses as the first through the 
P-th bits of the specific digital data signal. 
In the normal mode N, a specific counter 67 is connected to the comparing 
section 65 through the third selector 64 of the mode selecting section 
(61-64) and to the timing pulse generator 47 directly. With reference to 
the first through the P-th timing pulses in bit synchronism with the first 
through the P-th bits of the communication digital data signal, the 
specific counter 67 counts the output coincidence pulses produced in 
response to the first through the P-th bits of the specific digital data 
signal. The specific counter 67 thereby produces a number coincidence 
signal which indicates that the first through the P-th bits of the 
communication digital data signal represents the identification number 
specific to the radio paging receiver 60. 
The specific counter 57 supplies the number coincidence signal to the 
loudspeaker 28 through the speaker driver 29 as the speaker drive signal 
to make the loudspeaker 28 generate the call tone indicative of a call to 
the radio paging receiver 60 a predetermined time duration. 
The specific counter 57 supplies the number coincidence signal to a 
switching circuit 68 labelled "SW". In response to the number coincidence 
signal, the switching circuit 68 sends to the signal processor 30 the 
communication message signal CME (FIG. 2) which follows the call number 
signal CN. Responsive to the communication message signal CMR, the signal 
processor 30 makes the display unit 31 display the communication message 
of the communication message signal CME through the display driver 32. 
Turning to FIG. 6, description will proceed to a radio paging receiver 70 
according to a third embodiment of this invention. The radio paging 
receiver 70 comprises similar parts designated by like reference numerals. 
Like in the radio paging receiver of FIG. 1, the switch 39 is usually put 
in the off state and is put in the on state when the radio paging receiver 
70 is tested. The switch 39 corresponds to the mode selector 61 of FIG. 5 
and operates in the manner similar to the mode selector 61. 
In the radio paging receiver 70, the first through the third selectors 62 
to 64 and the comparing section 65 of FIG. 5 are implemented or 
constituted by logical circuits in the following manner. A combination of 
AND circuits 71 and 72 and an OR circuit 73 constitutes the first selector 
62 of FIG. 5 and operates in the manner similar to the first selector 62 
of FIG. 5. Another combination of AND circuits 74 and 75 and another OR 
circuit 76 constitutes the second selector 63 of FIG. 5 and operates in 
the manner similar to the second selector 63 of FIG. 5. A different 
combination of AND circuits 77 and 78 constitutes the third selector 64 of 
FIG. 5 and operates in the manner similar to the third selector 64 of FIG. 
5. A combination of the AND circuits 48 and 51, the inverters 49 and 50, 
and the OR circuit 52 constitutes the comparing section 65 of FIG. 5 and 
operates in the manner similar to those of the radio paging receiver 21 of 
FIG. 1. 
A reading circuit 79 corresponds to the signal supply lead 66 of FIG. 5 and 
operates in the manner similar to the signal supply lead 66 of FIG. 5. 
That is, the reading circuit 79 is connected to the timing pulse generator 
47 and the P-ROM 27 and supplies the first through the P-th timing pulses 
to the P-ROM 27 to read from the P-ROM 27 the first through the P-th bits 
of the directory number signal representative of the identification number 
of the radio paging receiver 70 in bit synchronism with the first through 
the P-th timing pulses as the first through the P-th bits of the specific 
digital data signal and to deliver the first through the P-th bits of the 
specific digital data signal to the AND circuit 74 corresponding to a part 
of the second selector 63 of FIG. 5. 
In FIG. 6, the photoelectric converter 40 is implemented or constituted by 
a phototransistor 80 having a collector and an emitter connected to the 
earth or ground. The collector is connected to the voltage source +V 
through a resistor 81. A collector voltage of the collector of the 
phototransistor 80 is supplied to the second waveform shaper 41. The 
photoelectric converter 40 operates in the manner similar to that of FIG. 
1. 
Turning to FIG. 7, description will proceed to a radio paging receiver 82 
according to a fourth embodiment of this invention and a test transmitter 
83 according to a fifth embodiment of this invention. Each of the radio 
paging receiver 82 and the test transmitter 83 comprises similar parts 
designated by like reference numerals. 
The test transmitter 83 has the encoder 33 which generates the test digital 
data signal. Connected to the encoder 33, the radio test signal producer 
34 produces the radio test signal RTS carrying the test digital data 
signal. The radio test signal is transmitted through the attenuator 37 and 
the antenna 38. 
Thus, a combination of the radio test signal producer 34, the attenuator 
37, and the antenna 38 serves as a radio test signal transmitting section. 
The radio test signal transmitting section (34, 37, 38) transmits the 
radio test signal RTS carrying the test digital data signal. 
The radio paging receiver 82 has the radio digital data recovering section 
(23, 24, 25) recovers the communication digital data signal from the radio 
communication signal CMS and the test digital data signal as a receiver 
recovered digital data signal from the radio test signal RTS. 
The radio paging receiver 82 comprises the emitter driver 35 connected to 
the first waveform shaper 25 of the radio digital data recovering section 
(23, 24, 25). Supplied with the receiver recovered digital data signal 
from the first waveform shaper 25 of the radio digital data recovering 
section (23, 24, 25), the emitter driver drives the light emitter 36 to 
make the light emitter 36 transmit the optical test signal OTS carrying 
the receiver recovered digital data signal. 
Thus, a combination of the emitter driver 35 and the light emitter 36 is 
operable as an optical test signal transmitting section connected to the 
radio digital data recovering section. The optical test signal 
transmitting section transmitting the optical test signal OTS carrying the 
receiver recovered digital data signal. 
The test transmitter 83 comprises the photoelectric converter 40 supplied 
with the optical test signal OTS carrying the receiver recovered digital 
data signal and the second waveform shaper 41 which produces the receiver 
recovered digital data signal. A combination of the photoelectric 
converter 40 and the second waveform shaper 41 serves as an optical 
digital data recovering section. The optical digital data recovering 
section (40, 41) recovers the receiver recovered digital data signal as a 
transmitter recovered digital data signal from the optical test signal 
OTS. 
A delay circuit 46' is supplied with the test digital data signal from the 
encoder 33. The delay circuit 46' gives the test digital data signal a 
predetermined delay so that a first bit of the test digital data signal of 
the encoder 33 coincides with a first bit of the transmitter recovered 
digital data signal produced by the second waveform shaper 41. The delay 
circuit 46' thereby produces a delayed test digital data signal. 
Thus, a combination of the encoder 33 and the delay circuit 46' serves as a 
test signal generator. The test signal generator (33, 46') generates the 
test digital data signal and the delayed test digital data signal. 
The timing pulse generator 47 is connected to the delay circuit 46' and 
generates a timing pulse signal in bit synchronism with the delayed test 
digital data signal. 
The comparing section 65 is connected to the delay circuit 46' of the test 
signal generator (33, 46'), the optical data recovering section (40, 41), 
and the delay circuit 46'. Like in the radio paging receiver 21 of FIG. 1, 
the comparing section 65 compares the transmitter recovered digital data 
signal with the delayed test digital data signal to successively produce 
bit coincidence pulses whenever the delayed test digital data signal and 
the transmitter received digital data signal are coincident with each 
other bit by bit. 
The first counter 53 is connected to the timing pulse generator 47 and 
counts up the first count in response to the timing pulse signal from the 
initial value to the predetermined threshold value to produce the count 
stop signal when the first count is counted up to the threshold value. 
The second counter 54 is connected to the comparing section 65 and the 
first counter 53 and counts up the second count in response to the bit 
coincidence pulses from the initial count to the increased count until 
production of the count stop signal to produce the count signal which 
represents the increased count as a receiver sensitivity of the radio 
paging receiver 82 in relation to the communication digital data signal 
RCS. 
Connected to the second counter 54, the display unit 31 displays the 
increased count represented by the count signal as the receiver 
sensitivity of the radio paging receiver 82.