The argument that the current 16-bit digital sampling offerings (Flex 6K,
ANAN-100/200, MB-1, etc) are insufficient in bit depth and sampling rate
doesn't hold water IMHO. Besides my own experience of no observable
overload during major DX and 160M contests, here are a few more tidbits to
consider:
http://www.eham.net/ehamforum/smf/index.php/topic,110479.0.html
https://community.flexradio.com/flexradio/topics/adc-overload-myths-debunked
etc etc
Barry N1EU
On Tue, Aug 16, 2016 at 7:43 AM, rick@dj0ip.de <Rick@dj0ip.de> wrote:
> EXCELLENT Gary. Thanks.
>
> I only disagree on the timeline. I don't think it will take so long.
>
> The MB-1 from Sun SDR or Sun Expert (not sure which brand they are
> pushing) "claims" to be what you described, but it costs $5K. However
> prices will drop rapidly as soon as competition is there.
>
> Within 3 years we will have it.
>
> In the year 2020, SDR with knobs a'plenty. (no computer required)
>
> BTW, has anyone actually seen or used the MB-1?
> I haven't heard a single user review yet.
>
> 73 - Rick, DJ0IP
> (Nr. Frankfurt, Germany)
>
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Gary J
> FollettDukes HiFi
> Sent: Tuesday, August 16, 2016 7:23 AM
> To: Discussion of Ten-Tec Equipment
> Subject: Re: [TenTec] OT: 7300 buy back program
>
> I agree that discussion of the general concept of direct conversion and
> SDR is relevant to this reflector regardless of brand. At some point, all
> radios will be of this design because it will be the cheapest possible way
> to produce a radio.
>
> I have not used the 7300, likely will not. I’d prefer an Omni 6+ that has
> SSB audio I can tolerate, a notch filter INSIDE the AGC loop and a
> standalone bandscope.
>
> The topic of digitization at this level was discussed ad-nauseum back in
> 1983 and 1984 as Compact Disk technology was just beginning as a
> “replacement for Vinyl records”. Things did not quite work out because the
> number of bits in the audio samples and the sampling frequency (44.1 KHz)
> required compromises that people with musical ears could easily hear.
>
> The move towards direct digital conversion and SDR is a replay of the same
> thing. If you don’t use enough bits in the sampling process, and don’t
> sample often enough, there is not sufficient dynamic range to allow for the
> wide variations in signal strength experienced on HF.
>
> Most good operators can copy signals that are within a few dB of the noise
> floor, especially in CW. These signals can easily be S1 or less on most
> good receivers, depending on band noise.
>
> The strongest signals (particularly in Europe with the big shortwave
> stations) can easily be 100 dB over S9 (48 dB) for a total signal dynamic
> range of 148 dB. 16 bit sampling only allows for 96 dB dynamic range. In
> order to get 148 dB dynamic range (3 dB dynamic range improvement per bit)
> you would need 32 bits minimum to handle the range.
>
> Keep in mind that, even though you are not LISTENING to that 100 dB over
> S9 shortwave station, the receiver is still seeing it as this is part of
> the spectrum that the DSP is trying to unravel to select your signal of
> choice.
>
> When the input to a digital device exceeds its dynamic range, the results
> are far from linear so artifacts, not really unlike severe overload in
> analog circuits, are heard, but often to a far worse degree than with
> analog systems.
>
> By analogy, the simple harmonic distortion produced in Vinyl by
> overdriving the cutting lathe were far more tolerable to the listener than
> the nasty aliasing that occurred from under sampling of audio signals in
> early CD recordings and the non-harmonic distortion that arose from the
> steps of quantization error with only 16 bit amplitude range, especially on
> soft notes whose bit level resolution was maybe two or three bits.
>
> As manufacturers learn this (Ten Tec included) things will get better, so
> long as the focus is on worst case receive scenarios. More bit depth and
> faster sampling rates will improve direct digital receivers to a point that
> they will be better than their analog counterparts. The marketplace will,
> however, dictate when that occurs.
>
> 24 bit 96 KHz sampled audio has been available technically for 15 or 20
> years using the DVD platform, but I have yet to see a disk that can offer
> it even to my damaged hearing. The marketplace preferred iPod(YUCK!) and
> MP3 (double YUCK!) because you could put 2000 “songs” onto a chip the size
> of a grain of rice, 100% of the songs being unlistenable sonically.
> Quantity wins out over quality for most people, especially if it’s cheap.
>
> Accepting a product with the obvious failings of poorly implemented direct
> detection creates a market for the junk (translation - entry level) and
> delays introduction of top performance designs.
>
> PS: I don’t want to have to have a PC running just to sit and listen to 20
> meters or to see a full scan of the band while I am doing something else.
> The only reason I don’t have an Eagle today is that getting a bandscope on
> it is a big PITA and I still need to have the PC running to use one.
>
> It will be a long time before TenTec or anyone else will offer a top
> performing fully digital receiver, with knobs and stand alone, so long as a
> trinket market exists for the performance level offered in the 7300.
>
> Gary
>
> W0DVN
>
> PPS: There is still no digital camera anywhere with the color depth to
> match old fashioned Kodachrome 64. 8 bits per color? Not enough! Same
> cause, same result.
>
> >
> > I am wondering about the same sorts of things. I bought a new Omni VII
> during the Fire Sale. I got it with the optional 300 Hz CW filter. Once
> the novelty wore off, I started getting annoyed by having to push a menu
> button, then scroll to a setting, and then select something like the
> setting the keyer speed, and do some other actions, just to do what a lowly
> knob does on my Corsair II and my MFJ keyer. So, that radio has found a
> new home. The Argonaut VI has a complex system of making adjustments, too,
> but it is much easier to use than the Omni VII, and seems to have a better
> receiver. I am using the Corsair II on HF again, and am starting to see
> why those people who also own one, or have an Omni VI, prefer them to the
> newer rigs. This was brought home to me rather abruptly with the recent
> threads on keeping Orion II rigs functional. With a rather obstructed trap
> vertical installed on a hillside, I am not going to set the contesting
> world on fire no matter what radio or radios I use. So, I can still prefer
> high performance radios that are getting on in years, like me, and are much
> less complex to use.
> >
> > Your Mileage will Most Certainly Vary...
> >
> >
> > Steve WA9JML
> >
> >
> > On 8/15/2016 1:16 PM, Mike Bryce wrote:
> >> I have a hard time handling over $1500 for a radio and being told it’s
> ‘entry level.’ Nothing like scaring the bejesus out of a new ham who after
> spending all that money for a rig, he/she ends up with ‘entry level’ radio.
> >>
> >> Does one really need a $4k/$5k radio to have fun with?
> >>
> >> How in the world did you guys survive contesting using the Triton IVs,
> the TS-520s, the FT-101s, and the HW-101s?
> >>
> >>
> >> Mike WB8VGE
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> > _______________________________________________
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> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
>
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