Ham Radio - truSDX transmitted audio and signal quality in SSB, AM, and FM.
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- เผยแพร่เมื่อ 23 ต.ค. 2022
- Sampling the transmitted audio quality of the little kit radio. Usable, but not great, yet. There may be improvements in future firmware releases, we'll see.
If you noticed the different case bottom with the built in stand, I put the model file up on thingiverse. Link here:
www.thingiverse.com/thing:556...
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There's going to be a follow up vid looking for ways to not overdrive and clip on SSB.
Thanks. This sort of thing is what ham radio with the (tr)uSDX is all about and what I look for in the videos. It's appreciated.
If I wanted to send/give you a microphone element to try what address should I use? Qrz?
Thanks, I'm looking forward to your thoughts and video
Both the onboard mic and speaker are emergency devices, add-on functions, the absolute minimum to get by on if needed. I think you can even use one of its buttons to send CW if you lack a key. Because assembled kits can be purchased from China, too many people seem to think this rig is a commercial appliance instead of a dirt cheap experimental rig. From tuning to interfaces to mic and speaker it's an experiment, a project radio. Yep, it works, and for the $60 in parts and ingenious software it's a many-mode multi-band rig that works pretty well and will serve a lot of poor hams around the world, giving them a chance to get on the air, and then embellish it as they learn and can get parts. But it's up to the hobbyist to make it work really well. That's the whole idea. We're hams, not CBers. We have a license to experiment, to do whatever we want with our radios, to design and build them from scratch, build a kit, or buy an appliance to plug into the wall and an antenna to plug into the back, our choice, it's up to us. We have a license to do it all. These rigs aren't appliances. They're projects. Hams have added variable voltage to their (tr)uSDX's to control output power, they tune the output toroids, they've added external speaker mics, even turned them into HT's - so far. That's just the beginning. I figure showing creative ways to solve problems and improve these little rigs are what the TH-cam videos are going to be about, and I'm surprised when I see them being reviewed, video after video as if they were Kenwood's or Yaesu's. They just aren't. They were never intended to be. These are for the people who dig into ham radio, not the super-CBers.
I got one a few weeks ago. For what it is, it's amazing. Even to just take a "deep dive" on how it works and the math behind the signal processing it's worth the $150 or so it cost.
I have a feeling the SSB problems are a result of the Amplitude (PWM) modulation and the Phase modulation being slightly out-of-sync with each other. SSB is the only mode where it has to both phase modulate and amplitude modulate at the same time. For CW and AM, it only has to amplitude modulate (via PWM) and for FM it only has to frequency modulate (by rapidly changing the frequency of the SI5351A). But for SSB it has to do both! If they are just a small bit out of sync with each other, you won't get a clean signal. Because the Si5351A is controlled by I2C data, getting it precisely timed with the PWM modulation will be a little tricky.
I bought the Pacific Antenna Electret Microphone kit fer $15 (1/2 to assemble) and it definitely improved the audio of my uSDX tx audio. 73/K6SDW
Same here...hope someone's told them that tube dia. Is too small!!
Works well.
Very good as always Kevin.
I've got one of these to play with for when the snow flies and I can't go outside. Based on your video Kevin, I'm glad I also have an 891 as well. Thanks for your time.
Glen
Thanks for another informative the video. Love my (Tr)USDX, but i have received several poor audio quality reports on SSB described as "distortion" or "overmodulation". Without hearing or seeing your RX transmission it is difficult to determine if using a different mic or changing the mic gain settings offers much improvement. By the way, I also had good success using the MX-P50M(with mod) and Minipa70 amplifiers with the radio. Not for QRP work, but it can help punch through pile ups.
Its a fantastic concept in terms of showing what is possible with so few components and inovative way of generating SSB, AM and FM. Would be great if it was based on a cheap ARM MPU instead of the Atmel since these are much more powerful and have enough flash memory not to need to compromise on features.
Excellent! There will always be a limitation to how good it can get with 8 bit processing but it would be nice to get it as good as we can. Really hard to know which steps help if you can't check the result. The best I have been able to do is to listen to myself over web sdr, usually sounds weak and not too clear but... it has been good enough to make contacts. It would be nice to make it better, so what you are doing is very good. Thanks!
Thanks Kevin, great video! BTW I saw your previous movie recommendation, 'Nomadland' and really enjoyed it. Hey, I was wondering if you have had any luck with half square antennas? Those seem to be interesting since they have some gain - I was thinking it could make a good video. Keep up the good work, Kevin!
I haven't tried a half square. That would be a challenge to set up since you need two masts and tension to keep the top flat. Remember, I'm living in an RV, I have to limit what I carry and my installations have to be temporary.
Thank you for sharing your test results. I just built one of these and it works fine except for SSB tx audio. I monitored the signal using another radio and no values for 3.2 Noise Gate or 3.3 TX drive provided adequate TX audio. I had several contacts tell me the audio was "scratchy". This plus the splatter as you pointed out, make me think it is overmodulating. Do you think a firmware change is needed or hardware? Thanks again, I always enjoy your videos.
Hi Kevin, looks like a fun radio! Hope to see you at Quartzfest. 73, Dave, KEØOG
I appreciate your honesty on the review. BTW, I figured how to shut off Adblocker for your specific channel here. I forgot about the Adblocker thing, until you mentioned it on a previous video. Thank you for your educational videos. K1QS.
Thanks for that! I didn't know they had some kind of URL specific option.
@@loughkb I was wrong. I thought you could choose a specific url. But It blocks out TH-cam entirely. Oh well.
Thanks, Kevin, this was helpful. Maybe you looked at CW in an earlier video, but I’m curious how it behaves there. It would be handy to have the voice modes, but CW is king.
Works pretty well on CW. There's already a few dozen vids of people operating it in that mode.
The filter can dial down quite narrow and doesn't ring. The AGC could be improved though. With QSB going on, the volume change can be quite dramatic.
Perhaps it was already said, but you were transmitting 4khz instead of 2.4khz. I would suggest trying that as well. Having said that, we can never expect this radio to produce the same signal quality as a more expensive rig.
Thanks for this video, keep them coming as these type of content helps the rest of us to understand our rigs better!
73 de Luis, HB9HJU
Yes, 4khz filter. However, in listening to the audio, and I did plot the spectrum later, it was rolling off below 2Khz, so there would be nothing above to modulate. So that's not it.
I used an old wouxan mic and old small headset and also earbuds. I’ve made numerous contacts including 3 qso’s to russia. Worked great on my station hex beam as well as mpas2.
Interesting test. In any case, an improvement will be welcome if it comes, but after all, today's quality is absolutely acceptable. I recorded my real QSOs via sdr radio (you can listen to them on my TH-cam channel) and I assure you that even in contest it is fine.
I’ve made over 130 QSOs on mine, as far as 2000 miles, all on SSB or FT8 with CAT. Never had any complaints about audio quality on phone. Amazing little rig. Your splatter seems worse than the TinySA output I’ve seen would indicate. Hard to know what is normal as they are all hand built.
I've never had any complaints either, with over a dozen SSB contacts.
Yours may be fine. I've heard from a few people that have also looked at their signal using another receiver since this vid went live. Some have clean modulation, others have distortion like mine.
Seems hit n miss.
That’s interesting. After this video, I tested mine on SSB. My audio seems just over 2KC wide, with no bleed over to the opposite sideband. I don’t have the same equipment as you to measure the signal, but used my FTDX101D while the (tr)uSDX was transmitting into a dummy load.
@@loughkb I tested again, all bands. I notice that this problem does occur for me when I’m not in the section of the band for which I’ve tuned to suppress harmonics. When I’m close (within 50-100 KC) of that spot for which I tuned the coils with the NanoVNA, the SSB looks much better.
Perhaps that might be a reason to dip the harmonics at a frequency within the SSB portion of the bands? I might have to play with this some more.
I’ll be interested if you or others can confirm better SSB characteristics near where the harmonics are best suppressed.
Tuned which coils? Are you talking about the LPF in the radio? It shouldn't be nearly that narrow and should be a low pass not a band pass filter. Something doesn't seem right there.
I can't see how anything in the RF section would affect the modulation, which is done in software. Unless, there's a problem with RF getting into the mic or audio chain before it gets to the atmega cpu.
Maybe there needs to be shielding between the RF board and the digital board.
@@loughkb Yes, the LPF coils, labeled Lx2 for x=1-5. And is it a pretty sharp dip. I’m not sure if it makes a real diffidence, but my SSB signal looked worst on 20m, but was much improved in the portion of the band for which I was tuned.
BTW, some to these as “2nd harmonic traps” and not low pass filters.
It shouldn't be a dip in a low pass filter, rather a drop off going up in frequency and no attenuation going down in frequency.
This is making me think it most likely is RF from the RF board getting into the circuitry of the digital board. I will probably make a shield to go between the boards and see if that fixes things.
@@KK4DF does that impact receive, transmit or both? And are you sure? Thanks
FM would be handy for working via gateways on 10m band :-) since my IC-756 has died I no longer have an HF set for /P operation, that wee beastie looks almost perfect! and would be so much easier to transport up into the hills around here, Ayrshire, S.W.Scotland. :-)
Might also play around with the "transmit drive" menu 3.3, Manuel says 4 is the best compromise and if you turn it up you get more compression and at 1 it's very linear. But some times reasonable minds will differ...
Thanks for that. I've been digging around a bit trying to find an explanation of what that setting is precisely for. I'll fiddle around with it after I get settled back in at the new location.
I think you can improve you measurement (wanted signal strength compared to unwanted / suppression) by having max hold on the top power over frequency indikation. These shades of yellow are really hard to judge wrt level, and a signal 50dB down might light up yellow still.
A signal that far down would only be a slight change in blue.
Can you check and verify truSDX receiver audio and signal sensitivity in SSB, AM, and FM ?
Can we have a video with this small radio receiving in AM and FM?
Will you be showing how to connect it up and use WSPR or FT8?
I'm going to build my own USB interface for it. Simple enough to be applied to any number of radios.
There's already a couple of vids out there on using the mic and audio jacks to do so with your computer sound card.
I would like to see the results using a good mike
The thumbs-up counter was at 555 and I kind of wanted to leave it there for a moment ;-) I pushed it to 556 anyhow.
This is helpful. Thanks! 72 - AA4K
The TruSDX does everything that a normal transceiver does using C++ for DSP.
I am still a tech only. Is this radio a kit? Thank you for demonstrating the audio quality.
KJ6VYF Dave
Yes, it can be bought as a kit for somewhere around 80 to 90 bucks.
You can also buy it already built for around $140
Good video and I have really enjoyed the way you have been mixing up content it has been a nice change of pace. Thanks for sharing. Vic de KE8JWE
Mine will be here in two days 😊
Get it yet? Love mine
@@chipweather I did! I just printed a different knob for it and designed a stand for my desk! It's a cool little radio!
@@DutchmanRadio sick. You have the stl?
Wow, the transmit audio is severely low pass filtered. The high end is completely gone. I wonder if a better quality external mic would have the same issue. As it is, something like the diagnostic rhyme test (DRT) scores for intelligibility would be really bad.
I like to see the comparison with IC-705.
Thank you. 73
There is no comparison. The 705 vastly outperforms it all around. It's an entirely different class of radio.
@@loughkb
Thank you for your input.
I gotta be real with you, a good portion of that splatter may be a side effect of how you have your SDR software configured.
Nope. Looks the same on my 705. A clean signal looks proper on it.
And, if you pay attention to the audio, you can hear the clipping distortion on the voice.
I guess it's not bad for a low cost transceiver.
Hello, dear OM Kevin,
you have to 'chanche' a view of your 'settings' in the menu, very, very carefully!
Do it realy carefull, and sensitive, ... ! Step by step, not from 0 to 100 (255) in half a second, ... !
- Less is more with the (TR)_U_SDX ! -
I made it that 'way' and my results are better then before, ... !
(From the 'standard values', the radio comes with, ...!)
It is an 'experimental SDR-radio' in every word, that Manuel said.
Each 'radio' will differ a little bit, (some more, some less) from radio to radio, on the hardware side. And then the software-part has to do the rest, and you, the 'user', has to do that very carefull!
There is lot of work, for a simple 8-bit controller!
Maybe, there are some glitches, we have to sail arround!
Hopefully, only by 'gently chanche' some parameter in the menu!
All together, the (small) hard-ware differences, and the new kind of SDR-software, to create a SSB-signal and demodulation, with the special kind in a new and 'different way', to buildt and use a 'Ham-radio'-TRX, will come together, and is 'not easy' to understand.
Some differences (bad SSB modulation, too loud or too low 'mike-gain', or other things ...) will occure, when the radio is in use, from radio to radio!
Most of the time, you can 're-adjust' some things, in the menu, and all will be 'right'.
Maybe some 'things' are not that easy to get right, but Manuel and Guido will do the best they can do! I'm sure, that it is that way!
Stay in 'tune' with Manuel on his HP and also on the forum, especialy made for the (TR)_U_SDX !
Look for any new details and hints, that will come in a regulary way, ... !
There are a many 'answers' to a lot of questions, that will come in the future, to find right now!
I should say: RTFM, ... but it's a lot to look for, ... for a 'simple experimental radio', that this two guy's implement, in the last two years!
It helps me a lot, during the 'bad times' in the 'Corona shut-down' periode, here in DL and I'm a proud 'user' of that 'special little QRP-radio' !
Please be aware that English is not my native tounge and when you find some mistakes in spelling and/or writing, please be so kind, 'collect' them carefull and recycle them in a 'professional' way, ... !
Thanks !
73/72 de Markus ; db9pz
(5 km/3 miles east of LX ; JN39FQ)
Ugh. Ugly audio, Kevin.
I'm wondering if the SSB transmission sounds " not so well "' because of the finals in this radio. Is it not Claas-E, that is used ?
It's generated by variying the output stage bias to create the amplitude envelope and rapildly reprogramming the frequency synthesizer to create the frequency components. At least that is as much as I can make out from looking at the circuit, the C++ Code and the description.