THE NRO STAFf 

Approved for Release: 2017/08/17 COS099723 

~J NATIONAL RECONNAISSANCE OFFICE 

WASHINGTON. D.C. 

MEMORANDUM FOR CHAIRMAN, SIGINT OVERHEAD 

RECONNAISSANCE SUBCOMMITT EE 

SUBJECT: Description of SIGINT Mis sion. 7239 (CONVOY II) 

The mission description for CONVOY II is attached to this 

lutter of transmitta 1. This SIGINT reconnais sance system is designed 

to meet the requirements of USIB-S-l 0.9/11 and USIB-S-IO. 9/13 . 

. OY II is a speoial purpose technical intelligenoe payload 

~ecl. to intercept signals from the DOGHOUSE, HEN HOUSE, and 

~radars. It will be launohed into a 75-degree inclination, 270-

uwtical-rnile circular orbit by a THORIAg~na booster from Vandenberg Air Foroe Base on 29 July 1969. CONVOY II is an integral part 

of the STRA W MAN II satellite which will also carry SIGINT mis sions 

71 C5 (Tl:-IRESHE:R) and 7234 (REAPER). 

SC..:(5, c •• \.H~ .. ""; tOche NRO on the operation of CONVOY II 

should inC.ll " ..1.;~;ired signals and signal cornbinations for which 

recordings sh()<.l~(; be made, areas for COJ\lVOY II operation, c)"2ected 

target signal anll)~;: ·.l(k levels, target ,.:·:orities relative to THRESHER 

anG REAPER targch;;, expected tc.1"get opc:::ating times, and freql,;.ency 

of collection. 

Attachment 

E .. ~ ;r:N F. SWEENEY 

Co .. v.,d, USAF 

Deputy Director for 

Satellite Operations 

Mission Description - CONVOY II 

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MISSION DESCRIPTION. CONVOY II 

I, GENERAL. 

COI\TVOY II is a special.purpose payload designed to gather Technical 

Intelligence (1'I) from the DOG HOUSE. HEN HOUSE, andl radars. 

CONVOY lIis designed to provide high quality predetection data to the Data 

Storage Unit (DSU) of the STRAWMA'NIIsate1lite. In addition, digital data 

are generated to indicate payload time and status •. and to provide measurement 

of the target signal frequency and amplitude. 

The primary purpose of CONVOY II is to detect and recognize the 

signals of interest. then to track and record the signals on the DSU. The 

system is capable of simultaneously recording two separate signals in order 

to detect coherence or cooperationbetweea the twO emitters. or, in "dualbeam" cases. between individual beams of the sarneemitter. The payload is 

capable of tracking signals in both frequency and amplitude. 

2. CONFIGURATION. 

The CONVOY II payload consists of.five sections, three which are 

directly applicable to system operation and two which are auxiliary in nature. 

The three operational sectionS are. the RF and Conversion Section, the IF and 

Predetection Section, and the Control Logic Section. The auxiliary sections 

are Power Supply and Telemetry. The configurations of the three operational 

sections of the payload are discussed below. 

2.1 RF and Conversion Section. 

Figure 2-1 shows the configuration of the RPand Conversion Section of 

the payload. Three separate antennas are employed, One for each of the three 

frequency bands. The signals from the 400)Vlliz and 900 MHz antennas are each 

separated into two channels by the diplexers shown. This separates the two 

beams of the DOG I-lOUSE an~ 1 radars. The 160 MHz antenna signal is 

passed through an image filter to permit single conversion. Each of the five RF 

outputs is applied to a controllable attenuator, an RF am plifier I and a bandpass 

filter. The attenuators are controlled in three steps of o. 30, and 60 db. This 

reduces the dynamic range requirement for the RF amplifiers to 42 db. The 

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RF amplifier provides from 15 to 25 db gain depending on the channel and is 

primarily responsible for establishing the receiver nOise figure. 

Two separately controlled frequency synthesizers are used to generate 

the injection signals for the five mixers . The syntheSizers are driven from 

a common crystal oscillator operating at 36 IvT.'dz. All injection frequencies, 

reference tOnes, and clocks are driven from this oscillator to maintain complete coherence through the processing channel. The synthesizers operate in 

the frequency range of approximately 260-300 IvIHz, with a resolution of 0.321 

MHz. The RF switching selects the d~esizer output and routes it to 

either a frequency divider or a doubler. The divided output (1.32-142 MHz) is 

used for low-side conversion of the 160 MHz signal to the nominal 21 MHz IF. 

The doubler outputs (539-579 MHz) are employed for high-side conversion of 

the 400 MHz si&'1lals to a first IF of 159 MHz. These outputs are also dOI,bled 

a second time to 1054-1178 Ml-Iz for high-side conversion of the 900 MHZ 

signals to a first IF of 201 lvII-Iz. 

The four outpucs of the first mixers are routed through amplifier-filter 

combi:1ations, then applied to the second mixers via mode-controlled RF 

switching. The second mi.xer injection frequency is 180 11Hz, obtained by 

multiply:.ng the 36 MHz oscillator by five. This results in high -side conversion 

of the 159 MHz signals, and low-side conversion of the 201 MHz signals I with 

the result at 21 NE-Iz in all cases. The payload logic selects the appropriate 

combination of the available signals and routes them to the IF section. 

2.2 IF andPrecietection Section. 

Figure 2-2 shows w1e IF and Predecectiol1 Section of the payload. The 

21 MHz outputs from the Conversion Section are routed through bandpass 

filters to the preamplifiers, which are foHowed by controlled attenuators. 

The IF attenuators provide steps of 0, 10, 20, and 30 db, and are controlled 

by the payload logic to maintain tIle output signal level within a 10 db dynamic 

range. The outputs of the attenuators are applied to the signal processing 

channels via selectable bandwidth filters and to the predetection channels via 

a blanking switch. The blanking switch is controlled by the payload logic dl1d 

inhibits the outputs of the predetection circuits until a valicl signal is recog11ized. 

The proceSSing channels consist of an amplifier followed by AM and FM 

detectors and threshold circuits. The threshold outputs control the payload 

logic, indicating both the presence or absence of signals and whether the sibmal 

is centered in the IF bandpass and in the amplitude dynamic range. 

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In the prec.1etection channels, a mixer converts tile IF signals down to 

tile 0.5-5.5 MHz band for recording on the DSU. The 18 MHz injection 

frequency is obtained from the 36 MHz oscillator by means of a frequency 

divider. The mixers are followed by limiters, ti18n filters and switches. In 

tile single sigl1al modes, one of the switcbes is energized, applying the limiter 

output directly to tile summing network. In the dual-signal modes, the two 

channels are attenuated 3 db, filtered to half bandwidth, and summed. The 

output of tile summing network is again filtered to remove harmonics from the 

limiting process. then summed again Witil a 6 MI-Iz reference tone (obtained by 

dividing the 36 MHz output) and twenty keyed tones, which indicat.:; ~~,,~H~~~s, I ., 

of the control lines for tile attenuators and frequency syntllesizers. iJ'The,: cor.l- i 

posite signal is matched to tile 75 ohm line of the buffer amplifier, which 

drives the DSU. The idealized spectrum of the composite signal is dhow~~ ~n 

Figure 2- 3. The bandwidtils and limits shown refer to the 3 db points. The 

numbers above ti1e figures refer to the predetection output frequency, and the 

numbers below ti1e figures show tile corresponding frequency in the IF channel 

before tlle last conversion. 

2.3 Control Logic Section. 

The payload control logic , shown in Simplified form in Figure 2-4, 

includes tile receiver control logic. the recognition logic, and those parts of 

the payload associated Witil operating sequences and external digital interface. 

The timing-generator, operating from a 1 MHz clock derived from the master 

oscillator, provides tlle time reference for the various logic functions. The 

10 KHz clock for the marker word generator is also produced by the payload 

logic. 

The control logic relays are magnetic latching relays driven by the 

command programmer. The states of these relays condition the control logic 

to select the appropriate RF and IF signal channels and operating sequences. 

Two essentially identical recognition and processing channels are controlled 

by tile mode relays. Each channel consists of recognition logic, scan and 

track control, frequency and amplitude tllreshold logic, and the control circuits 

for the frequency synti1esizersal1dRF /IF attenuator control. Either or both 

channels may be operating independently. 

The recognition logic consists of analog timing circuits and comparison 

logic tilat monitors the parameters of detected signals and compares those 

parameters. with the preset limits to determinewhethertlle signal is to be 

recorded. Once recognition is established,thesystemis conditioned to track 

the Signal, andti1e DSU request logic is enabled to initiate recording. The 

recording continues as long as the recognition criteria are satisfied. The 

recognition and tracking sequences are discussed iri detail in Section 4. . CONTROL HO BYE-12917 - 69 

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The marker word generator produces a serial, 48 bit status word to 

the DSU digital track each time the vehicle clock pulse is received. This 

word contains time from the resettable time accumulator, payload identification, 

and the status of the control relays. 

3. CHARACTERISTICS. 

3.1 Recognition Criteria. 

When COi\TVOY n is searching far HEN HOUSE 01'1 ~o recognition 

parameters are employed: pulse width (j?W) and pulse repetition interval cPRI). 

Common limits are set for both pulsed emitters, These limits are 200 to 1200 

usee on PW and 8 to 64 msec for PRI (15.6-125 pps). It is possible to bypass 

both critelia by ground command. 

When searching for DOG HOUSE, CONVOY II employs dliferent techniques. The search mode incorporates an environmental survey due to the 

presence of interfering CW signals in this band and because;; of the desirability 

of rapid reacqt:isition during the sweep retrace. This survey establishes the 

presence and stores the frequency of any non-sweeping CW emitters. These 

signals are ignored c1ming search and reacqUisition but are used when verifying 

a valid intercept as described in secti.on 4.2.1. Initial recognition of DOG 

HOUSE requires that a Sig11al be present for more than 200 usec. Final recognition is accomplished by a check of frequency sweep rate after tracking is 

initiated. This check requires a sweep rate in excess of 125 MHz/sec and a 

signal duration in excess of approximately 4 milhseconds for recognition. The 

4-millisecond minimum duration criterion is employed to discriminate against 

BMEWS interference, which could result in false alarms under certain conditions. 

The recognition criteria can be bypassed by ground command. 

3.2 Threshold Sensitivity. 

The CONvOY system processing threshold for all frequency ranges is 

-87 dbm at the input to the payload. On the two dual-beam signals, this value 

is increased by 4 to 5 db in the beam overlap region. System sensiti.vity can 

be reduced by ground command in two steps of 30 db each if dense interference 

environments are encountered. The sensiLivity control is independent for the two 

processing channels. The processing threshold signals level results in a predicted worst-case signal-to-noise ratio of 12 db at the predetection output. 

Target effective radiated power (ERP) of -+- 50 to .. 90 dbm will produce a threshold 

signal level to CONvOY II. 

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3.3 Frequency Coverage. 

The frequency bands which are monitored by CONVOY n are a 

function of the target(s) and whether the receiving channel is operating in 

scan or track. Specific frequency coverage is controlled by the Digital 

Command Programmer andccnsists of various combinations of the frequency 

bands of interest. The available combinations are as shown in Table 3.l. 

When searching for a single sigrral, the synthesizers are tuned to center the 

predetection signal at 3.0 MHz. In the dual signal modes, the two signals 

are frequency multiplexed into two 2.25 MHz bands cel1tered at 1. 625 MHz 

and 4.375 MHz. The 3 db scan and track frequency limits are shown in 

Table 3.2. 

3.4 Inputs. 

*'""' t 

3.4.1 Antennas. 

The three RF inputs to CONVOY II are similar In all characteristics 

except frequency range. Each input is designed to interface with a stub 

antenna, connected by means of RG-142 BjU. 50 ohm cable and OSM miniature 

connectors. Signal levels ranging from - 87 to +6 dbm, referred to the input 

connectors, are detected al1d tracked over the frequency ranges shown in 

Table 4. 1. In the diplexer eros sover regions at 402.5 MHz and 915 MHz. this 

range is shifted upward by a maximum of 5 db. Antenna and feedline VSWR 

shall not exceed 3,0 to lover the indicated frequency ranges. 

3.4.2 Power. 

The CONVOY payload is designed to operate from an unregulated dc 

power source with a nominal output of 23 volts. The system is designed to 

accommodate variations from 22 to 29 volts while operating. Continuous 

application of input power as low as 19.0 volts shall not result in failure or 

permanent degradation of the system. 

Two power supplies are employed, The auxiliary supply operates continuously and is used for the system time accumulator, the temperature monitors. 

and for certain critical logic circuits. The main power supply is controlled by 

external command and provides the internal voltages necessary for system 

operation. 

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CONVOY II Signal Receiving Combinations and 

Channel Assignments 

TABLE 3.1 

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3.4.3 Commands. 

Control of the CONVOY payload is accomplished by means of magl1etic 

latching relays, driven by the Digital Commar;.d Programmer. These relays are 

capable of storing the last commanded state without consuming power, and are 

designed to be compatible with the command programmer outputs. 

3.5 Outputs. 

3.5.1 Analog Data. 

Predetection signals and fixed-frequency tones are output 011 the analog 

track of the DSU. These signals are frequency-multiplexed onto the 30 Hz to 

6 MHz passband of the DSU. The predetection data appears as either a single 

5 MHz wide channel centered at 3.0 MHz or two 2.25 MHz wide channels 

centered at 1. 625 and 4.375 MHz. respectively. A continuous reference tone 

is recorded at 6.0 MHz, and 20 keyed tone channels which are spaced at 20 

KHz intervals from 40 KHz to 420 KHz are used to indicate receiving channel 

status. Six tones are used for each of the two frequency synthesizers, and four 

tones are used fOr the attenuator state in each of the two channels. 

Signal levels are controlled to maintain the composite signal output 

within the dynamic range of the DSU. The output circuit is· designed to match 

the 75 ohm nominal input impedance of the DSU. 

3.5 • 2 Digital Data. 

The data recorded on the USU digital track consists of a 48 bit marker 

word which is generated ata bit rate of 10 kbps at intervals of 125 milliseconds 

and is synchrOnized to the 8 pps vehicle clock. The word contains payload 

identification, payload statu$~ and vehicle time data. The word is generated 

in three-level RZ form. 

3.5.3 DSU Request. 

The DSU request line is used to switch the DSU input to the CONVOY II 

analog and digital outputs , via the STRAWMANII priority assignment logic. 

The DSU request line also commands the DSUto initiate rec.ording. The 

command cortsists of a relay.contact closure connecting the line directly to the 

positive uniegtl1ateovehiclebuss. 

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4. OPERATIONS. 

4. 1 Search Phase 0 

The search phase of system operation is initiated by commanding 

payload enable and is restarted following the reset interval which ocCUrs 

whenever the selection of signals -of-interest is modified. The search operation consists of scanning the selected frequency bands in steps and sampling 

for a minimum threshold. Appropriate IF bandwidths and detector time constants are selected by the payload logic to be compatible with the frequency step 

size and dwell. During this phase, signal output from the predetection circuits 

is inhibited. 

When DOG HOUSE is a target, a peri0dic presearch environmental survey 

is performed to minimize interference due to the presence of non-sweeping CW 

emitters in tile frequency band, The band is scanned in steps as described in 

the following paragraph. Presence of a signal on the same frequency step for 25 

msec shall cause that signal to be identified as non-sweeping CW and not a sienal 

of interest. This survey is performed at intervals of approximately 5 seconds, 

unless a valid intercept has been detected. The results of the survey are stGred 

and subsequently used to prevent acquisition of these interfering signals. 

The search process is initiated after completion of the environmental 

survey when searching for DOG HOUSE or immediately after payload enable 

when searching for HEN HOUSE orl I The payload;;ontinues to scan the 

band in steps as indicated in Table 3.2. At each step the system dwells for 

6 usec to allow time for synthesizer stabilization and filter delay. During this 

interval, the processing channels are sampled and the presence of an in-band, 

over threshold signal is stored. If the signal is present on a step for a sufficient 

number of successive samples to total 200 usee, the minimum signal dUration 

confirm is satisfied and, for DOG HOUSE signals, the acquisition phase shall 

be initiated. For HENHOUSE and he duration must be between 200 and 

1200 usec in order to initiate the acquisition phase. In either case, the scan 

terminates 011 the confirmed frequency step, When searching for HEN HOUSE 

o~ I scan continues if detected signals are of either insufficient or 

excessive duration. 

4.2 Acquisition Phase. 

4.2.1 DOG HOUSE. 

Initial recognition of a DOG HOUSE-type signal enables the automatic 

amplitude and frequency tracking sequence andunblanks the analog data output. 

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Six usec are allowed for stabilization, after which the tracking threshold 

circuits are sampled and the controls adjusted one step as required. A delay 

of 48 usec elapses before a second sampling is performed. After the first 

two samples, resamples are performed at 48 usec intervals. The acquisition/ 

track phase frequency coverages, step size, number of steps, and correction 

thresholds are as shown in Table 4.1. The amplitude thresholds are spaced 

at approximately 10 db and the correction step size is 10 db in all modes. 

Final recognition (acquisition) of the DOG HOUSE signal is made on 

the basis of minimum sweep rate and minimum signal duration by requiring 

a minimum of two frequency corrections ,in the same directHm; within 5 msec. 

Further, the signal must remain above threshold for a minimum of 4 msec 

before a final recognition is indicated. The minimum sweep rate requirement 

is approximately 128.6 :tv1Hz/sec. and, if the signal meets.these requirements, 

the tr.ack phase is initiated. 

If the sweep rate criterion has been satisfied, the CW survey storage 

is interrogated to determine whether the system has tracked into a step containing known CW. If it has, the search phase is immediately resumed with 

the receiver gain returnedtommdmum. Tfthe step is hot knowIito contain CW , 

a 25 msec interval is allowed for resumption offrequency sweep. If this interval expires, the CW storage is modified to.reflect the newly detected CW, then 

search is resumed. Search is resumed immediately if· at any time during ti1e 

acquisition and confirmation process the signal drops below the signalindicate 

(S1) threshold, which is nomin:ally3db below the minimum threshold level. 

4.2.2 HEN HOUSE and '-----~~~--," 

The acquisition aIi~confirlTIa:tiori.p~·9Cessfor HEN I10USE ah~ liS 

not initiated until the PW confirm~'This ca.llsesthescanto stop on the indicated 

frequency step, unbl~nk the.analQgolltput$. ~torethe state$of tlle.8ttenuator 

and synthesizer control ccuinters,>.and initiate .an8t064. msec.PRLconfii'mation; 

No frequency or amplitude corrections ate perfolined untilrec;E:ipt of a second 

SIt Reception of a secondSI initi~te~tl1t:lPV(confirI1l checkand.also initiates 

frequency and amplitude samples:c:urd correc:tiohs6usecafterthe leading edge of 

51 and at 48 usec intervals there;liter aslql1g as the 81 rell1ains; Disappearal1ce 

of S1 WitlloUt a i'd confirmcauses·theaqenuilto'rand synthesize:rcQntr91s to 

be reset to the storedstate.APWeonfi~l1l.~ccurring priorto.tlleminifnum PR1 

limit shaD result in immediate re1ilfn tome search operation. Similarly , 

expiratiofl of the max~mumPRIWit110utde.tE;c;tibn:ofa PWeonfirm Tesultsin 

resumption· of the ·searchQperation .•. APW:'conf1x-moccurring within ,:he 

permissible interval initiates th<=trCickplj.asc;:. . 

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Approved for Release: 2017/08/17 COS099723 

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Approved for Release: 2017/08/17 COS099723 

TABLE 4.1 

FREQUENCY COVERAGE, ACQUISITION/TRACK PHASE 

HEN HOUSE: 

50X1 

DOGHOUSE~erJ: 

Mode 2 0.643 63 2.0 - 4.0 

Mod.e 6 0.643 63 0.625 - 2.625 

Mode 10 0,643 50 3. 375 - 5.375 

Mode 12 0.643 63 3,375 - 5.375 

Mode 3 0.643 63 2;0 - 4.0 

13 O~643 63 D. - 2. 625 

O. 643 0.625 - 2.625 

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l. 286 63 2. 0 - 4.0 

1 .. 286 (J 3 O. 625 - 2. 625 

51 3 . 375- 5.375 

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Approved for Release: 2017/08/17 COS099723 
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Approved for Release: 2017/08/17 COS099723 

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CONTROL S'I'ST1::M 

4.3 Track Phase. 

Upon initiation of the track phase by either of the means described 

above, the payload logic immediately issues a DSU request to begin recording 

of the recognized intercept. This occurs in all modes except those which 

select the HEN HOUSE signal in combination with any of the other four. In 

these modes. recognition of the HEN HOUSE signal alone does not result in a 

DSU request. 

In the track phase, amplitude and frequency continue to be sampled at 

48 usec intervals as long as 81 is present, and corrections are made as required. 

The action at the disappearance of 81 is a function of the signal(s) being processed. When the DOG HOUSE signal is lost, CONVOY II immediately reverts 

to the search operation, full gain is commanded, and reacquisition is attempted. 

The analog is blanked, but the DSU request remains active for approximately 

five seconds after the last sweep rate con.firm indication. 

When HEN HOUSE andD are being tracked, S1 disappearance is 

expected at the end of each pUlse. In general, the procedure followed at this 

time is to hold the last frequency setting and increase the receiver gain by one' 

step (10 db). In those modes in which thel Isigned is being processed in 

the lower predetection channel, the frequency control counter is advanced one step 

at the end of each pulse. This is done to accommodate.a 0.8 or 1. 6l\1Hz interpulse frequency shift of th~ ~igna1. This eliminates the possibility of lOSing 

lock due to the signal shifting out of the processing channel frequency limits. 

These settings are maintained untilSI isagairi detected. If the SI is invalid, the 

original settings are reset. If the 81 is valid, recording and tracking continue 

as above. Lack of a confirmed pulse within the maximum interval(i. e. , loss of 

signal or LOS) initiates the search operations, increases receiver gain to maximum, and blanks the analog output until reacquisition occurs • The DSU request 

remains active for approximately five s((~onds after the la8t PRI confirm 

indication. 

4.4 RecognitionCriteria Bypass. 

The ree og11itiol1 criteria for PW, PRI, and frequency sweep rate can be 

bypassed on command. These bypass commands modify the search, acqUisition, 

and track sequences as follows. 

The PW confirm bypass eliminates the 200 to 1200 usec requirement 

for pulsed signals, such that any pulse greater than 4.5 usee is processible. 

vVhen searching forDOG HOUSE, this bypass removes the minimum signal duration 

reqUirement from the search and reacqUisition sequences. 

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The PRI bypass is applicable only to HEN HOUSE andC It 

eliminates the minimum and extends maximum PRI requirement. When the 

PRI recognition criteria is bypassed, COJ\TVOY II will recognize any pulses 

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of correct width with an interval not greater than 250 msec. When this bypass 

is actuated in conjunction with the PW bypass, the system recognizes any 

threshold signal, including CW. Signal disappearance causes immediate 

resumption of the search mode. 

The: sweep rate confirm bypass is applicable only to the search for 

DOG HOUSS, and eliminates the requirement for frequency variations in the 

sig11a1. When the sweep rate confirm is bypassed, the system recognizes and 

records any signal with a duration in excess of 200 usec, including non-sweeping 

CW signals. When bypassed in conjunction with the PW bypass, any threshold 

signal with a duration greater than 55 usec gel1er~tes a DSU request and is 

tracked and recorded. 

In all cases described above , the DSU request line remains active for 

a period of approximately five seconds after the last recognition has occurred. 

4.5 Reacquisition of Targets. 

When the selected signal of interest disappears after recognition, 

reacqllisition is attempted ,Reacquisition differs from the normal search and 

acquisition phases only in that the DSU request is still present since the track 

phase had been selected prior to LOS. The time required to reacquire a signal 

is a function of the operating mode, the signal parameters, and the states of 

the recognition criteria bypass relays. 

For normal operation against HEN HOUSE andli LOS is not 

detected until expiration of the maximum PRI timer (6~ without detection 

of a valid PW. Assuming that the LOS indication was caused by a frequency 

shift (as at the end of a scan period). detection of the first pulse after LOS 

could require an additional maximum pulse repetition period. followed by an 

additional period before a PRI check is obtained. A worst case value for 

reacquisition in normal operati6nisapproximately 3 x 64 : 192 msec. 

With the PW confirm requirement bypassed. the same reacquisition 

sequence is followed, and the same maximum 192 msec limit is valid. However, 

it is possible that the PW of the signal may be significant by comparison. A 

worst case delay would result if the last recognized pu~se was very narrow, then 

no signal was detected and the maximum PRI timer expired. If the first detected 

signal was near the ma..'Cimum width which would still be recognized as a pulse, 

the overall reacquisition time would approach 4 x 64, or 256 msec. 

CONTROL HO BYE-12917-69 

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Approved for Release: 2017/08/17 COS099723 

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When the PRI confirm is bypassed, LOS is not detected until two 8 pps 

clocks have been received, or a maximum of almost 250 msee. Following 

that, the first valid PW detected would result in reacquisition, so the maximum time required would be 250 msec plus one PRI plus one PW. With both 

PW and PRJ confirms bypassed 1 any threshold signal is recognized and search 

is initiated at the end of each detected signal. The maximum reacquisition 

time in ti1is mode is equal to the intervals between detected Signals, plus the 

delay due to the finite scan period (84 usee maximum). 

When tracking DOG HOUSE, reacquisition is again a function of tile 

signal parameters, ti1e environment, and the status of the bypass relays. Two 

distinct phenomena can .initiate the reacquisition process: LOS or loss of sweep 

rate confirm. LOS results in immediate initiation of the search phase. The 

first signal which remains above tiueshold for 200 usee, and which is not a logged CW Signal, is acquired and tracked until a sweep rate confirm is received, 

5 msec expire, or LOS again occurs. The time required to lock to the proper 

signal is highly dependent on the interference environment and upon the characteristics of the DOG HOUSE signal during the "retrace" interval. 

When the PW confirm is bypassed, ':he 200 usec minimum signal duration 

requirement is deleted. This does not normally modify the time required for 

reacquiSition of the desired signal. 

With the sweep rate confirm bypassed, any signal present for 200 usec 

is acquired and recorded as long as it remains above the system processing 

threshold. Time required for reacquisition is thus 200 usec plus one scan 

interval (66 usee maximum). With bothPW and sweep rateconiirms bypassed, 

reacquisition time is determined solely by the environment, as each signal 

present is acquired and recorded until LOS. 

4.6 Commands. 

COr-...rvOY II can be commanded into various operating modes. These 

modes control the combinations of signals-of-interest which are selected, allowable receiver gain rang~s, and the types of recognition criteria and recording 

requirements which are employed. The mode control logic automatically selects 

the appropliate RF sections, local oscillators, and IF channel for the desired 

signal combinations. 

The following functions are performed by ground command. 

• Power On/Off 

• Payload Enable/Disable 

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• Signal Selection 

• Minimum Attenuation Control 

• Recognition Criteria Bypass 

• Search Phase Blanking Bypass 

Power On/Off enables the internal main power supply by controlling 

the drive current for the switching transistors, The auxiliary power supply 

remains enabled at all times. 

Payload Enable allows the system to begin searching for signals-ofinterest, and to begin generating digital marker words for status indication 

and time cOiTelation. During periods when this relay is released (payload 

disabled), the system generates the time referenc(~ code to indicate the 

disabled state. This time code occurs for 60 to 100 usec each time a time 

update pulse is received from the vehicle clock. The marker word is also 

generated at these times. 

Signal Selection defines the combination of signals which shall be 

processed. Thirteen differentcohlbinations are available (see Table 3,1), 

selected by the states of the five relays. Each signal combination is comIllandable by either of twO relay co.mbinations. The two combinations are complementary to provide redundancy in the event of .relay or command failure. 

Changing of the signal selection is possible with the payload enabled. Any 

change in relay states under these conditions produces a logic reset lasting 

for 125 t0250 msec. DUTing this reset interval, the analog system outputs 

are blanked except for the generation of the time reference code. 

Minimum Attenuation Controlliniits the maximum available receiver 

gain for each of the two independent processing channels. Zero, 30, or 60 db 

of attenuatiohcan be selected. Automatic amplitude tracking is employed 

above the .mihimum commaridedsignal input level. Change in attenuation is 

possible during payload operation with no n'lore than momentary interruption 

in the analog output data. 

Recognition Criteria Bypass allows the payload logic to bypass any 

combination of the PRI, PW, or scan rate signal recogpjtion criteria. Search 

Phase Blanking Bypass aUowsthe payload logic to bypass blaJ:L1.cing of DSU data 

when CONVOY II is not tracking a valid radar signal. 

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Approved for Release: 2017/08/17 COS099723