[Lowfer] Question about SDR Dongle with Win-XP

Chris Wilson chris at chriswilson.tv
Tue Oct 9 06:11:53 EDT 2018


Hello Andy,

 Tuesday, October 9, 2018

 Be aware Tony Parks of Five Dash Softrock fame has retired and I
 *THINK* the kits are no longer available, although I did read that a
 few kit options appeared on the web site recently but were "Sold Out"
 within a day or two. You occasionally see unbuilt kits turn up and
 some built ones in the amateur for sale groups. They are superb value
 and worth tracking down! The Kiwi SDR is great, but quite expensive.
 I use a Red Pitaya (also not exactly cheap but versatile with so many
 well sorted firmware options available) and run the HDSDR software on
 the available firmware, it has proven to be reliable and with a cheap
 Ebay pre amp brilliant on LF. I am pretty sure it will run on XP but
 haven't tried it. HDSDR will run on XP for sure. You could also look
 for a basic Sofrock Lite II IF receiver, they could be ordered with a
 455kHz crystal for single band MF usage and are simply converted for
 LF. They too work superbly on a decent aerial.

 It would be great if Tony could be persuaded to at least make bare
 PCB's available, I have hinted at it but I guess retired is retired
 and he's certainly already given a lot to the amateur world at great
 value for money :)


Best regards,
 Chris    2E0ILY       mailto:chris at chriswilson.tv


AKvL>  Hi Clint:
AKvL> Thanks for the info.. That's a lot to think on.. The Softrock,
AKvL> or possibly better, a KIWIlooks like a better way to go over the
AKvL> RTL dongles... It might be time to consider thechange to Linux
AKvL> as you mention for these old dinosaurs.. The still work just as they
AKvL> were designed to do, and I hate to " throw them away "... 

AKvL> 73 for now:
AKvL> Andy - KU4XR

AKvL>     On Monday, October 8, 2018, 1:04:59 PM EDT, Clint Turner <turner at ussc.com> wrote:
AKvL>  
AKvL>  Hi Andy,

AKvL> There are several "moderately-priced" options:

AKvL> While one of those $20 RTL-SDR dongles may look attractive - and will 
AKvL> (more ore less) work for LF (if you get one that does "direct" input 
AKvL> such as the "RTL-SDR.com" sells - AND if you remove the DC power 
AKvL> insertion jumper as noted in their documentation) the "only 8 bits" of
AKvL> A/D conversion is a huge factor.

AKvL> There are those (more expensive) with built-in "up-converters" (e.g. 
AKvL> they take LF/HF signals and convert them up to >100MHz) rather than 
AKvL> using the "direct" mode:  Even though they may have 1ppm TCXOs in them,
AKvL> you'll likely see a bit of drift on very narrow-band signals.  Whether
AKvL> or not this mixer is good down to LF/MF - or even capable of the dynamic
AKvL> range of the device itself depends largely on how well-engineered it 
AKvL> was.  (I personally avoid the up-converter if it's reasonable to do so.)

AKvL> While I am (sort of) able to get away with this sort of thing on the 
AKvL> "AM-160-120M" receiver on the Northern Utah WebSDR, this is possible 
AKvL> only with with (what is possibly over-the-top) levels of filtering 
AKvL> coupled with judicious amounts of amplification (see: 
AKvL> http://ka7oei.blogspot.com/2018/02/managing-hf-signal-dynamics-on-rtl-sdr.html
AKvL> )

AKvL> The upshot is that these dongles are "marginally usable" for anything 
AKvL> other than the VHF/UHF frequencies for which they were designed - but 
AKvL> there are a few things that *may* make them usable - particularly in 
AKvL> light of their very low cost:

AKvL> - Use a band-pass filter only for the frequency of interest. (Usually a
AKvL> good practice no matter what).

AKvL> - Carefully set the RF input level so that they will "clip" (maximum 
AKvL> A/D) only occasionally under "strong signal conditions".

AKvL> - Even more important is to set the level so that under "quiet" 
AKvL> conditions that you are always "tickling" the bottom 2-3 bits: 
AKvL> Under-driving (too-low signal) is arguably more deleterious than 
AKvL> mild/moderate overdriving.

AKvL> - To do the above, the software needs to have some way of monitoring the
AKvL> raw A/D levels as it may not be difficult to find the "sweet spot" - or
AKvL> even know if you are over/under driving without it.  I don't know if the
AKvL> available RTL-SDR dongle programs for Windows even have this capability.

AKvL> As for which will work with XP:  You may need to dig around and find 
AKvL> some old drivers as the current crop of drivers from "Zadig" do *NOT* 
AKvL> support XP.

AKvL> * * *

AKvL> Another option that will probably yield */far superior/* results 
AKvL> (because of much better RF circuitry and the use of an A/D converter - a
AKvL> sound card - with 16 bit depth) would be to use an "Softrock" type 
AKvL> receiver.  Ones that I would recommend are those from "fivedash.com" and
AKvL> there are two to consider:

AKvL> - The "LF/MF" version of the Softrock Ensemble II.  As a kit it's in the
AKvL> $70 range and a pre-built is already available This is a self-contained
AKvL> receiver with switchable band-pass filters that can cover from 
AKvL> 130kHz-3MHz - provided that you use a 192 kHz sound card (the local 
AKvL> oscillator, as designed, doesn't really go much below 200 kHz unless one
AKvL> added another divide-by-two and reconfigured the USB interface chip to
AKvL> account for that - both of which are easily done, but not well 
AKvL> documented.  I use this for monitoring the range for monitoring the 
AKvL> range that includes the 2200 and 1750 meter bands and it works well.

AKvL> - A modified "Softrock II Lite" receiver, available as a kit for around
AKvL> $20.  If your PC already has a half-decent sound card (which will 
AKvL> probably be only 48 or 96 kHz sampling rate) this may be the most 
AKvL> economical option. The Northern Utah WebSDR uses this for its 630 meter
AKvL> band receiver (a receiver for covering 2200-1750 is available, but 
AKvL> pending some infrastructure work to allow the installation of an antenna
AKvL> that will work <250 kHz) and I have documented how this may be done, here:

AKvL> http://websdr1.utahsdr.org/info/rx_equipment.html#lf_mf_receiver

AKvL> This shows the revised input filtering and modifications for these 
AKvL> receivers to work at 630 and also 2200-1750 meters, including revised 
AKvL> band-pass filters that are specifically designed for 2200-1750 and also
AKvL> 630 meter use, being optimized for use with a 96kHz sound card - needed
AKvL> if you plan to cover 2200+1750 meters.  (A lowly 48kHz sound card is 
AKvL> find for 630 meters.)

AKvL> Not shown in the diagram - but described elsewhere on the above page -
AKvL> is how these are interfaced with the $18 "SoftRock" kit (from QRP labs) 
AKvL> as the local oscillators:  The QRP labs kit can produce up to 3 LO 
AKvL> signals, so just one of these will produce the two LOs needed for 
AKvL> 2200-1750+630 meter coverage.

AKvL> The /second/ option (the modified Softrock II Lite) is almost 
AKvL> hardware-agnostic:  As long as you can find some sort of program that 
AKvL> will run on your computer and do the audio processing, you will be 
AKvL> fine:  Older version of programs like HDSDR, etc. work and I've used 
AKvL> them in the past on XP machines.

AKvL> * * *

AKvL> If you have old hardware kicking around, one should not completely 
AKvL> ignore the possibility of using them with a "ham radio" version of Linux
AKvL> (free!) that will do everything you need, and be more "lightweight" in
AKvL> its processor and memory requirements. There are some "live boot" (e.g.
AKvL> run from a DVD or thumb drive - no need to install to try them out, you
AKvL> can install later) "ham radio" distros out there with which one can 
AKvL> test, but it would require a bit of a learning curve.  There are a 
AKvL> number of programs in these Linux distros that will work with both 
AKvL> dongle and sound-card based systems.

AKvL> I hope that this helps.

AKvL> 73,

AKvL> Clint

AKvL> KA7OEI


AKvL> On 10/7/2018 4:29 PM, Andy - KU4XR via Lowfer wrote:
>> Greetings all:
>>
>> The quickest way to obtain information ... ask those who ARE ... I have a couple of windows XP machines that
>> I would like to possibly put back into service as a " Remote Receiver " setup using a Dongle and software..
>> As always, I am budget oriented, so, which Dongles, and which Software will work with Windows XP ??
>>
>> Thanks for information, and 73:
>>
>> Andy - KU4XR
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