Many thanks to SWLing Post contributor, Dan Robinson, who shares this video by OM0ET:
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With all the sellers of the ats120 online, if there an official site to ensure not getting a crippled clone?
(Like the “tiny sa” market has been proven to be aware of faulty clones)
> I would really love if even just 1 of these DSP radios could give the SSB/ECSS audio quality that the Tecsun PL-680 has…….oh I almost forgot, the Sangean ATS-909 X2 has really great audio, I don’t fully understand how they made it sound so good, I think they implemented the DSP differently.
The ATS-909X2 does it much the same as the previous ATS-909X (which, by the way, also uses a Si473x chip for both AM & FM detection/demodulation) – standard traditional RF & IF chain, carrier re-insertion using a BFO, with the Si473x being fed with the IF signal. It’s is essentially doing AM demodulation of the IF signal (BFO carrier + 1 sideband).
The cheaper “DSP” radios – like this – that people complain about having poor SSB are doing the whole shebang in the Si473x, and it’s pushed right to its limit to do that.
FWIW, the Tecsun PL-660/680 demodulates SSB much the same way the much-lauded Sony ICF-2010/2001D did it – right down to using a clone of the IC used for synchronous detection. That’s why it’s so good at it.
https://www.skyworksinc.com/Application-Pages/Automotive-Radio-Infotainment make the Si series of chips. Please do not quote Si###x The x does not appear they all have 4 digit numbers and different characteristics.
The only one which is Si4730 claims short wave reception but no claim to decode SSB.
It has a low frequency intermediate frequency so the filter to exclude all but the wanted signal can have very steep sides, eliminating more noise particularly for the other sideband and the suppressed carrier.
The critical characteristic in SSB reception is the local oscillator being exactly the frequency of the carrier which was suppressed prior to transmission. If this does not happen the pitch is changed, if it is bad enough it is called ‘duck talk. Since DSP radios use a master oscillator which is divided by a ratio to get the tuned frequency. This device says it has an automatic frequency control which is fine for FM and AM, but not for SSB because there is no frequency reference which in AM would be the carrier. They don’t on the online specification sheets give a tolerance on the frequency accuracy of the oscillator in non FM modes.
> Please do not quote Si###x The x does not appear they all have 4 digit numbers and different characteristics.
There’s a whole series of them; the Si473x series chips are all very similar, differing slightly from one another mostly in ancillary functions (e.g. RDS/RBDS) and bands, with many of them (e.g. the Si4730/31/34/35) sharing the same datasheet.
That datasheet, by the way, itself refers to them as “Si473x” throughout, starting with literally the first sentence of the description on the first page…
> The only one which is Si4730 claims short wave reception but no claim to decode SSB.
False. The Si4732, Si4734, and Si4735 *all* support shortwave – and, most amusing to me, the Si4730 you said does, doesn’t! (At least officially – I’m aware some later batches *can* be unofficially used at SW.)
And at least the Si4732, Si4734, and Si4735 have custom firmware/patches from SiLabs/Skyworx that’s available to OEMs to enable SSB. It’s well documented that’s how so many of them from major manufacturers (e.g. the Tecsun PL-880 and later radios) *do* support SSB. Maybe try pulling one apart sometime and looking for yourself, rather than guessing?
(There’s also leaked/ripped/hacked/reverse-engineered firmware made available on the net by various experimenters for other experimenters. I’ve not mentioned those because they’re probably of dubious legality, but I’m pretty sure the whole ATS-20/20+/25/120 range as based on those firmwares.)
So, thanks but no thanks Alan – I think I’ll keep following the manufacturer’s lead and continue to refer to them in general as “Si473x” unless there’s some specific reason to single out a specific chip in the lineup.
The rest of what you wrote is your usual irrelevant infodump that either misunderstands or has no direct connection to what I wrote, so I’ll just let it go and leave it for others to decide.
I got one a couple of weeks ago and it’s a decent radio with a good external antenna, my 134 foot long EFHW 49:1 it handles very well and I was surprised at how well it worked on Medium Wave without any noticeable overload.
SSB distortion has improved a lot over the ATS-25+ which is pretty bad in my opinion.
There is notable FM bleed over in the SW bands, I have around 4 x 200 Kw FM transmitters around 40 Kms from me which probably doesn’t help. The LNA doesn’t help here either but you need it when using the whip.
It works best in the hand on the whip due to grounding.
I wish the antenna could swivel because when standing up it blows over quite easily and since you can change the screen orientation it’s a shame the FM antenna can’t swivel.
Bluetooth works well.
I have a couple of videos up on youtube. https://www.youtube.com/@o00scorpion00o/search?query=ats-120
The ATS-25 used to overload badly, however, since the permanent shut down of our local 252 Khz Longwave transmitter I have not noticed overload so it is probably down to the closure of 252 Khz.
These radios lack front end filtering so if near strong AM transmitters it could be an issue. Though the same goes for many radios, the PL-310 ET will absolutely die with external antenna at night, compare to the PL-330 it’s a night and day difference as that little 310 handles strong signals far better.
Sadly, while SSB distortion has improved the low frequency cut off remains which is common on most of these SI47xx chips and it makes for very thin audio when using ECSS it just never sounds good and while the speaker on the ATS-120 is pretty tiny, even using headphones it doesn’t change that fact, but as I said, it’s common with the DSP radios.
I would really love if even just 1 of these DSP radios could give the SSB/ECSS audio quality that the Tecsun PL-680 has…….oh I almost forgot, the Sangean ATS-909 X2 has really great audio, I don’t fully understand how they made it sound so good, I think they implemented the DSP differently.
I installed the Bernard Binns FW and it din’t change things much. Perhaps a future update.
I haven’t yet installed the WifI Antenna. Audio over bluetooth sounds good.
Still, at the end of the day, I much prefer, the PL-680, great ECSS performance and audio and SSB audio + tuning around is really a great experience compared to the constant chuffing of many of those DSP radios.