[amsat-bb] Icom IC-9700 and Kantronics TNC

[W3AB/GEO]

I don't know if the 9700 has TX EQ. The 7600 does.

Hmm, you just triggered something about TNC's I'll research.

⁣___
Sent from my two way wrist watch
73 de W3AB/GEO​

On Sep 6, 2020, 15:00, at 15:00, Tim N8DEU <n8deu at outlook.com> wrote:
>What audio EQ?
>
>9612 or IC-9700?
>
>If you are talking about the Treble and Bass settings on the IC-9700,
>they had no significant impact in decoding the transmitted signal.
>
>
>Best Regards,
>Tim Cunningham - N8DEU
>
>
>
>
>
>From: W3AB/GEO<mailto:w3ab at yahoo.com>
>Sent: Sunday, September 6, 2020 4:23 PM
>To: Tim N8DEU<mailto:n8deu at outlook.com>
>Cc: amsat-bb at amsat.org<mailto:amsat-bb at amsat.org>
>Subject: RE: Icom IC-9700 and Kantronics TNC
>
>Very good Tim. Thanks for diving in so deeply.
>BTW, have you tried the TX audio EQ?
>___
>Sent from my two way wrist watch
>73 de W3AB/GEO
>On Sep 6, 2020, at 13:48, Tim N8DEU
><n8deu at outlook.com<mailto:n8deu at outlook.com>> wrote:
>
>
>I stopped guessing and started measuring. The data holds the answer
>after a deeper dive into this issue.
>
>
>The audio is not distorted.
>
>
>The problem with the ICOM IC-9700 and both Kantronics 9612 and KAM XL
>setups is a very old problem. I knew something seemed familiar about
>the decode problem, but it was 33 years ago. After measuring the
>IC-9700 signals on a service monitor and viewing the signal on an
>oscilloscope hooked to a Kenwood TH-D7a headphone jack, the picture was
>very clear. I discovered the old twisted audio problem where the higher
>2100 Hz tone is much lower in amplitude than the lower 1300 Hz tone.
>Why does this matter? The XR2211 demodulators had immense trouble
>decoding packets with this condition and so does the TH-D7a with a
>Tasco modem, but the Tasco modem decodes ~50% of something where the
>XR2211 does not decode anything.
>
>
>When (Amplow*cos(FreqLow)) is close to the same value as
>(Amphigh*cos(FreqHigh)) the performance is not good on an XR2211
>decoder nor a Tasco modem chip. Early in the days of 1200 baud TAPR
>packet modem designs it was discovered the higher tone needed to be 20
>dB higher. In other words, you at least need some pre-empahasis on the
>transmit signal for it to be decoded and obtain some noise reduction.
>There is no pre-emphasis on the transmit signal from the IC-9700
>Accessory Port based on the results I measured. The low tone is about
>1.47 times higher than the high tone relative to the deviation
>measured. When I measure the two tones levels with an oscilloscope tied
>to the TH-D7a headphone jack, I measure the low tone is 1.29 times
>higher than the high tone.
>
>
>Both of the audio tones output from the Kantronics 9612 are the same
>level at roughly 50mV. Thus, the 9700 clearly alters the signal levels
>on the two tones in a less than desirable fashion!
>
>
>I have not tried sending audio through the microphone connector yet,
>but I would hope it would at least have pre-emphasis for better results
>on boosting the high tone.
>
>
>Before I pass judgement, I will present the data to ICOM on the topic.
>Hopefully, the response I get will be better than what my friend
>received from them. They claimed to him the TNC keys the radio and it
>passes the audio as if they have no problem in the equation. In their
>defense, they did not understand the problem, but they did not pursue
>it either. Their response was correct from a simplistic view, but what
>their radio does or does not do with the audio can break everything.
>Pete, N4YOT, found if he sent 2 duplicate packets back to back with his
>KAM XL, the transmitted packet would be decoded. This raised the
>possibility the TXDelay might be the culprit initially from his
>results. However, that gets into the 50% packet decode rate.
>
>
>When I hooked up my Kantronics 9612 on my end to the IC-9700, I
>experienced the same problem as Pete and he worked on this for the past
>2 months getting nowhere and little help from ICOM. I finally hooked up
>the 9612 to the IC-9700 to take a look for myself. It quickly became
>obvious there is a lack of pre-emphasis on the high tone when the data
>is transmitted. In fact, the emphasis is on the low tone or the high
>tone is being attenuated!!! The end result is poor decoding of that
>transmitted signal when the low tone is higher in amplitude than the
>high tone. There is indeed a problem with the ICOM IC-9700 using the
>Accessory Port with 1200 baud packet.
>
>
>This requires a hardware modification on the 9612 to implement a filter
>to reverse these effects unless ICOM can provide some insight on how it
>can be accomplished with their radio where the problem exists.
>
>
>Let's see what ICOM has to say with the detailed measurements I
>collected.
>
>
>
>
>Best Regards,
>Tim Cunningham - N8DEU
>
>
>
>
>From: GEO Badger<mailto:w3ab at yahoo.com>
>Sent: Sunday, September 6, 2020 1:28 PM
>To: Tim N8DEU<mailto:n8deu at outlook.com>
>Cc: amsat-bb at amsat.org<mailto:amsat-bb at amsat.org>
>Subject: RE: Icom IC-9700 and Kantronics TNC
>
>
>Tim,
>
>It seems a modulation issue of some type.
>
>I don't have a 9700 but I do have a 7600 and had a modulation
>distortion problem. When using the accessory port insure that "DATA OFF
>MOD" is set only to "ACC", not "MIC+ACC". All the others should be set
>to "USB".
>
>___
>Sent from my two way wrist watch
>73 de W3AB/GEO
>On Sep 5, 2020, at 22:00, Tim N8DEU
><n8deu at outlook.com<mailto:n8deu at outlook.com>> wrote:
>
>I made several measurements with the deviation starting at 0.75 kHz up
>to 4.00 kHz in 0.25 kHz steps. At each step 10 packets were transmitted
>and multiple receivers were used for decoding. At no point did the
>success rate go above 50% decoding. At 3.25 kHz and 3.50 kHz the
>transmit decode rate was 50%. All other settings were less.
>
>
>
>The Kantronics 9616 cannot drive the IC-9700 any higher than 4.07 kHz
>deviation and that level is achieved at XMITLVL = 114. Increasing the
>XMITLVL does not produce any additional increase in FM deviation using
>the square wave tone from the CALIBRATE mode.
>
>
>
>I have worked with 1200 baud packet for 33 years and set up quite a
>number of systems and this one will require some more observation. The
>same Kantronics 9612 connected to a Yaesu FT-736 or and an FT-847 show
>a 100% packet decode rate at 1200 baud. Both of these radio’s work fine
>at 9600 baud which is something not mentioned anywhere for the IC-9700.
>
>
>
>I was checking to see if others are having issues with the IC-9700.
>This started with a friend asking questions for the past 2 months about
>having trouble with the IC-9700 connected to a KAM XL and I walked him
>through all the logical steps. Finally, I decided I better try hooking
>my 9612 up to the Accessory Port to see how it works. This should not
>be too complicated. My results were exactly the same poor results he
>encountered on transmitting 1200 baud packets.
>
>
>
>Increasing TX Delay does nothing to help as that does not seem to be
>the issue.
>
>
>
>1200 baud packets are decoded through the receiver perfectly fine.
>
>
>
>The problem is transmitting 1200 baud packets for a successful decode
>rate on the IC-9700 through the Accessory Port.
>
>
>
>
>
>
>
>Best Regards,
>
>Tim Cunningham – N8DEU
>
>
>
>
>
>
>
>From: GEO Badger<mailto:w3ab at yahoo.com>
>Sent: Saturday, September 5, 2020 3:00 PM
>To: Tim N8DEU<mailto:n8deu at outlook.com>
>Cc: amsat-bb at amsat.org<mailto:amsat-bb at amsat.org>
>Subject: Re: Icom IC-9700 and Kantronics TNC
>
>
>
>Can you look at the deviation?
>
>
>
>---
>Ciao baby, catch you on the flip side
>
>
>73 de W3AB/GEO
>
>http://www.w3ab.org
>
>You can say "over", you can say "out", you just can't say "over and
>out".
>
>
>
>
>
>On Friday, September 4, 2020, 08:59:04 PM PDT, Tim N8DEU
><n8deu at outlook.com> wrote:
>
>
>
>
>
>Simplex is the only method I tried at this point to keep it simple.
>
>
>
>Two different IC-9700 Radio radios, one with a Kantronics 9612 and one
>with a Kantronics KAM XL. Both using simplex and both exhibiting the
>same results.
>
>
>
>
>
>- Tim
>
>From: AMSAT-BB <amsat-bb-bounces at amsat.org> on behalf of W3AB/GEO via
>AMSAT-BB <amsat-bb at amsat.org>
>Sent: Friday, September 4, 2020 6:52:05 PM
>Cc: amsat-bb at amsat.org <amsat-bb at amsat.org>
>Subject: Re: [amsat-bb] Icom IC-9700 and Kantronics TNC
>
>
>
>Tim,
>
>Have you tried simplex contacts?
>
>⁣___
>Sent from my two way wrist watch
>73 de W3AB/GEO​
>
>On Sep 4, 2020, 14:53, at 14:53, Tim N8DEU via AMSAT-BB
><amsat-bb at amsat.org> wrote:
>>Has anybody interfaced a Kantronics 9612 or the KM XL TNC to the
>>accessory port of the Icom IC-9700?
>>
>>The reason I am asking is there are two IC-9700 users using the same
>>firmware who are experiencing the same issue with both of these TNC’s.
>>Packets are decoded with little to no issue on the receive side, but
>>the transmit side is a different story.
>>
>>It seems only about 30% of the transmitted packets are decoded by
>other
>>stations using 1200 baud. The deviation of the transmit signal and the
>>TX delay are not the issue. The same TNC works with no issue on a
>Yaesu
>>FT-736 and the FT-847.
>>
>>
>>Thank You,
>>Tim Cunningham - N8DEU
>>
>>_______________________________________________
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>_______________________________________________
>Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
>to all interested persons worldwide without requiring membership.
>Opinions expressed
>are solely those of the author, and do not reflect the official views
>of AMSAT-NA.
>Not an AMSAT-NA member? Join now to support the amateur satellite
>program!
>Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb