MDO3024 vs MSOX3024T - USB 2.0 (LS/FS) - Page 1
Forum section: electronics / testgear

author: onemilimeter
author_rank: Frequent Contributor
timestamp: September 15, 2015, 01:01:57 am
content: I wish to purchase a mixed-signal scope (i.e. with the 16 digital channels) and currently have two options (Tektronix MDO3024 and Keysight MSOX3024T) in mind but still can not decide which one to buy. Both have a bandwidth of 200MHz.Tektronix and Keysight offer add-on application modules for the scopes. However, I found out Tektronix offers MDO3USB (USB serial triggering and analysis (LS, FS)) application module for MDO3024, whilst Keysight does not offer such similar application module for MSOX3024T. Keysight only offers such similar application module (i.e. DSO4USBFL - Low and Full-Speed USB 2.0 triggering and analysis) for its MSOX 4000 series scopes.My question: is there any limitation in MSOX3024T that prevents Keysight from offering USB 2.0 Low-Speed and Full-Speed triggering and analysis?Thanks.

author: bson
author_rank: Unknown
timestamp: September 15, 2015, 01:17:15 am
content: Can't decode high speed USB 2.0 on a 200MHz instrument; it requires 1GHz or greater bandwidth.A 200MHz instrument can only decode low speed and full speed.

author: onemilimeter
author_rank: Frequent Contributor
timestamp: September 15, 2015, 03:27:07 am
content: Quote from: bson on September 15, 2015, 01:17:15 amThanks bson... both are 200MHz scopes...Tektronix offers MDO3USB (USB serial triggering and analysis (LS, FS)) application module for MDO3024.However, Keysight does not offer such similar application module for MSOX3024T. I wonder is there any limitation in MSOX3024T that prevents Keysight from offering the similar application module.

author: JoeB83
author_rank: Regular Contributor
timestamp: September 15, 2015, 03:59:54 am
content: I can't tell you whether or not one of the two will work specifically for USB, but I'd HIGHLY recommend the Keysight scope over the Tek for general use.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: September 15, 2015, 05:32:50 am
content: Quote from: onemilimeter on September 15, 2015, 01:01:57 amThe USB 2.0 option for the Tek MDO3000 is worthless if applied to a MDO3024, and even for a 500MHz MDO3054 it's not very useful.As bson said a 200MHz scope is completely insufficient for USB 2.0 analysis, which is really something for a 1+GHz mid-range or high-end scope with sufficient processing capability and not a slow low-end device like the Keysight DSOX3kT/MSOX3KT or Tek MDO3k.For a new scope, you'd be looking at something like the LeCroy WaveSurfer 10 with the USB2 decode options:http://teledynelecroy.com/oscilloscope/oscilloscopeseries.aspx?mseries=470It's cheaper than a 500MHz DSOX3kT or MDO3054 but still sets you back $10k for the scope alone.

author: marshallh
author_rank: Unknown
timestamp: September 15, 2015, 06:26:29 am
content: Do you really need a scope for decoding USB2? Unless you're developing your own PHY or taping out an asic, use someone else's and follow standard SI practices for diff pairs. You can check with a 1ghz bandwidth scope to verify nothing went completely pear-shaped, but it's really hard to screw up.In that case you will be much better served getting a USB2 protocol analyzer which is designed to show you what you want to see, and has a vastly superior UI for debugging.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: September 15, 2015, 08:24:27 am
content: Quote from: marshallh on September 15, 2015, 06:26:29 amI'm not sure a 1GHz scope plus a separate USB 2.0 protocol analyzer is cheaper than a 1GHz scope with USB2 decode option, especially when with some bit of haggling the manufacturer might throw in the USB2 option for a reduced price or even for free.

author: VK5RC
author_rank: Unknown
timestamp: September 15, 2015, 09:07:13 am
content: I have been a very happy owner of the KS brother, a DSOX3024A, it has behaved well even despite the odd earth loop f**k up! Yes some more memory would be excellent but has never really limited me, unlike my brain (or lack of , HiHi)I bought the multi-update software key but rarely use those features.Excellent layout, haven't used the Tek but I suspect that it is pretty good as well.

author: Howardlong
author_rank: Super Contributor
timestamp: September 15, 2015, 10:46:45 am
content: Quote from: bson on September 15, 2015, 01:17:15 amOP asked for Low Speed and Full Speed USB 2.0, not High Speed.In short, USB 2.0 != USB High Speed.However in specifying USB 2.0 LS and FS, the OP may be doing OTG which is part of the USB 2.0 and above spec.USB 1.0 & above:Low Speed 1.5MbpsFull Speed 12MbpsUSB 2.0 & above:OTGHigh Speed 480MbpsUSB 3.0 & above:Super Speed 5GbpsUSB 3.1 & above:Super Speed+ 10Gbps

author: Howardlong
author_rank: Super Contributor
timestamp: September 15, 2015, 11:12:21 am
content: Quote from: onemilimeter on September 15, 2015, 03:27:07 amMSOX3000 offers USB Low Speed and Full Speed triggering out of the box but there are no options for USB protocol analysis. You need the 4000X and 6000X series for that.