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My Kenwood TH-D74 and ICom 7300 both have the ability to output IF instead AF. Is this IQ signal at 12ksps, meaning 12kHz of bandwidth, or something else?

What are some projects that can be done with these? Seems most digital modes work just fine with normal audio. Or is this for if I want to RX/TX digital modes up to 12kHz?

Or only good for an extra wide waterfall?

Thomas
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3 Answers3

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The 7300's "IF output" is a USB digital signal at 48kSPS, the same as the USB AF output (and you can only have one or the other at a given time). It places the dial frequency at an IF frequency of 12kHz, and you can get a maximum bandwidth of around 16kHz (+/- 8kHz from the dial frequency) which is dependent on the selected mode and filter settings, so you need to have the AM or FM mode selected on the 7300 to get more than a few kHz of bandwidth (yes, this is strange).

Mostly it's useful for one thing, which is listening to DRM (Digital Radio Mondiale) HF signals using an IC-7300 and a PC; the IF mode is the only way to get the 10kHz-wide digital signal to the software, since the filter can only open up to 3.6kHz wide in USB-D mode.

hobbs - KC2G
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Page 18-2 of the IC-7300 full manual and page 12-2 of the TH-D74 User Manual describe a 12-KHz IF output signal. The IC-7300 manual suggests demodulating a DRM signal using software installed on a PC, but you could demodulate any signal present on the IF output, not just DRM.

natevw - AF7TB
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Brian K1LI
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  • The D74 manual link is a local C:\ link. And the IC7300 full manual link gives permission denied. This link works for the latter: https://rigreference.com/storage/manuals/icom/ICOM-IC-7300_ENG_CD_5.pdf--5a4c89c34bb990.19925823.pdf – Thomas Apr 05 '21 at 17:22
  • Thanks, I got the bandwidth of the IF signal wrong. I still don't understand what it is, though. IQ data? – Thomas Apr 05 '21 at 17:24
  • Kenwood even states "Special PC software is required to process IF signal or detection signal. JVCKENWOOD does not provide any support regarding the procedure to connect to a PC or the PC software." – Thomas Apr 05 '21 at 17:27
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    @Thomas no, it's not IQ, it's real samples at an IF of 12kHz. – hobbs - KC2G Apr 05 '21 at 20:20
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The 7300 is a direct sampling SDR. Thus, the 7300's "IF" output is really some sort of a splitter off of its RF input. So this "IF" output can be used for connecting a second full HF receiver, SDR or otherwise, or custom panadapter, or even a spectrum analyzer covering the entire HF band.

The TH-74D "IF" output appears to be wider in bandwidth than when used for demodulated audio, useful for capturing (skimming) multiple digital signals, often with FTx (et.al.) found both inside and outside (above and below) the usual SSB bandwidths at the same time. Perhaps the same for CW skimming (simultaneous multiple frequency Morse Code decoding) more of entire CW sub-bands as well.

hotpaw2
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  • The entire HF band? But isn't it only 48kSPS, per the other answer? That's not even enough for the whole 30m band. – Thomas Apr 05 '21 at 21:00
  • This product description claims the full HF RF bandwidth: https://www.dxengineering.com/parts/log-ptrx-7300/reviews – hotpaw2 Apr 05 '21 at 22:42
  • But it goes on the inside, not using the same port. – Thomas Apr 06 '21 at 12:46
  • "...the 7300's "IF" output is really some sort of a splitter off of its RF input." This doesn't agree with the IC-7300 manual. – Brian K1LI Apr 08 '21 at 20:55
  • The manual is incorrect. You have to install an internal adapter to get real IF output. – hotpaw2 Apr 08 '21 at 23:24