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Best pc design for SDR
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Mike German
There has been discussion on this group recently about the minimum requirement in terms of performance for a pc but I am interested in very low noise (RFI) configurations.
I have a second hand oldish Dell laptop that looks after a couple of SDR and as far as I can tell does not introduce any inherent noise to the received signal (near 2m). I also have a new HP laptop and as soon as that starts up the noise levels go up. This appear to be radiated noise and is not cured by running on battery nor with ferrites. So, I am looking for advice on generic types or specific makes or pc or laptop for radio work. For example are the mini pc more emc tight? Are there any laptops (other than my old Dell) that you have found to be particularly good? Or am I just unlucky with the HP :-( regards Mike |
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Mark Cayton <mcayton@...>
Hi Mike,
You speak of a computer being "emc tight" but I'm not certain that that's the real problem (or concern). I have a full-size desktop computer case (tower) that has a humongous see-thru window in the side of the case (It's a gaming machine, see pic), with no RF shielding across the window at all. I was hugely worried that I wouldn't be able to even use the machine because of my concerns over RFI getting out, but it turns out that that machine is as quiet as any other computer in the house (we have 5, and at least 3 are running 24/7). I've been using it for a year now and I have yet to detect any RF emanating from that machine at all. I also have an inexpensive Dell Inspiron 15-5548 (i5 dual core laptop) that I purchased two years ago from the Microsoft Store for less than $500 shipped, that's also blessedly RFI-free. I used it for SDRC duties before I bought the big gaming machine. Then there's my wife's new Dell Inspiron 3668 midsize desktop (i5 quad core) purchased less than a month ago ($499 shipped) that's also completely silent. My point is you don't need to spend lots of money to get a quiet machine, and even a wide-open see-thru window in the case doesn't necessarily equate to RFI getting out (at least with the right components inside). Maybe I've just been lucky with my choices in computers but I'd like to believe (wishful thinking) that my situation is the norm rather than the exception, with modern computer offerings. 73, Mark KF5VQY https://drive.google.com/open?id=0B77dlHbMDWmJZ08tRkdYNm4tWEhtX1AyVDVZRFQyRF9mY0FV |
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Siegfried Jackstien
years ago i worked for a company that produced (modded) pc systems for military ... there is no such thing as emc tight ... but you can lower the level many dbs ... all cablings (internal and external) got extra ferrites (even
when there is already one installed from manufacturer we mounted
additionally SEVERAL of them a dozen of them cause you have all kinds of cables on a modern pc, keyboard, mouse, printer, monitor (and maybe other things) the pc cases also were modded (extra shieldings and/or groundings, small slits in the case closed with conducting tape all these modding brought nearly nothing when only one of them were made ... but in sum it brought many many db ..... these mods were done for military cause some clever hacker can "spy on you" just with receving the rfi from your pc ... getting this radiation lower was the goal ... completely eliminating would be best ... but we never could get it below the level of our sensitive test equipment in the rfi chamber you should look for a full metal case (not a gamers pc with
windows to see inner parts) ... add ferrites to cables close "slits" in the metal case (they are the main source for rfi around 100-200 megs) proper grounding and adding also ferrites to the (usb?) cables to your sdr hardware and putting the sdr away from the pc with a longer cable may also help a bit every db counts!! dg9bfc sigi Am 03.02.2018 um 11:56 schrieb Mike
German:
There has been discussion on this group recently about the minimum requirement in terms of performance for a pc but I am interested in very low noise (RFI) configurations. |
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Lawrence Stoskopf
Guess we are looking at preWW2 Navy RX. Two RF amp stages in front of the mixer to stop LO radiation, etc. we call the Boat Anchors! N0UUu
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Oidar
On Sat, Feb 3, 2018 at 03:56 am, Mike German wrote:
This appear to be radiated noiseHave you concluded that it is radiated noise? My experience is that conducted noise is far more common than radiated noise. Wrapping at least the antenna and the power cables, on some suitable ferrites, may reduce the conducted noise significantly. However, If it is radiated noise, i concur with Sigi. //Mats |
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Mark Pettifor
Based on some older conversations a couple years back on some SDR forum (don't remember which), I've purchased and have had good results with a Lenovo W530 laptop, although I wasn't having good luck with a setup I have up in Michigan at a remote location. I think the antenna wasn't far enough away from the power supply. The feedpoint was about 50 feet away, and I had coax going from there into the shack, so maybe the coax wasn't up to snuff. I have a hard time believing that 50 feet isn't far enough away to minimize or eliminate any radiated noise from the PS. Anyway, the PS is pretty noisy, so it must be kept as far away from the antenna as possible.
What I like about the Lenovo is that the sound is excellent, when using headphones. It's almost like there's some kind of "noise cancellation" circuitry being used. Hard to explain, until you hear it. I'm trying to figure out a way to use some 12V DC marine batteries to power the laptop. The laptop needs 19V input, so somehow I need to transform the voltage from the batteries to 19V. I only get about 3 hours max with the "extended life" battery that I got with the laptop when DXing with a SDR attached. Mark |
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chutton12000
Marl:
To power your laptop from 12 VDC, you have a couple of options:
You can get a 12VDC laptop PS. eBay has plenty for car usage. Get the right connector and enough power and all us well.
You can find power packs on eBay with 19VDC output. They have large Li ion batteries. Some have 12 vdc inputs for charging.
You can find a DC to EDC converter. Finding one that accepts 12 VDC abd outputs 19 VDC should be no problem.
All are potential sources of RFI so a partocilar unit may or may not be a problem.
Chuck
Chuck From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of Mark Pettifor <mark@...>
Sent: Sunday, February 4, 2018 1:04 PM To: main@SDR-Radio.groups.io Subject: Re: [SDR-Radio] Best pc design for SDR Based on some older conversations a couple years back on some SDR forum (don't remember which), I've purchased and have had good results with a Lenovo W530 laptop, although I wasn't having good luck with a setup I have up in Michigan
at a remote location. I think the antenna wasn't far enough away from the power supply. The feedpoint was about 50 feet away, and I had coax going from there into the shack, so maybe the coax wasn't up to snuff. I have a hard time believing that 50 feet isn't
far enough away to minimize or eliminate any radiated noise from the PS. Anyway, the PS is pretty noisy, so it must be kept as far away from the antenna as possible.
What I like about the Lenovo is that the sound is excellent, when using headphones. It's almost like there's some kind of "noise cancellation" circuitry being used. Hard to explain, until you hear it. I'm trying to figure out a way to use some 12V DC marine batteries to power the laptop. The laptop needs 19V input, so somehow I need to transform the voltage from the batteries to 19V. I only get about 3 hours max with the "extended life" battery that I got with the laptop when DXing with a SDR attached. Mark |
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Alan Melia
Mark the radiation 'from' a laptop is usually from the power supply as you suggest. Think radio.....the ac power source is usually two wire though there may be a 3 pin connector (as my think-pad) First check there is safety groun connection on the supply lead. If it is not the the X-rated supression caps have nowhere to divert the switching noise to. A clip on ferrite can help but put two three turns through it. The DC supply side is floating. (this means the who system is one long antenna. Ferrite the DC lead as well. As far as the lappy itself is concerned ground the frame using the lugs on the VGA connector or and other visible/touchable metal.
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This can make a significant difference. If not is the power supply a branded Lenovo unit, If not throw it away and get a branded one.....it will probably cost twice as much but will be worth it. I am afraid my experience is the laptops are not the best things to use for radio, though with effort they can be made to work.(I prefer a metal cased desk top with a modified PSU (3A filtered socket exchangedfor the normal cheap 3pin input connector. Put ferrites over the coax near the PC as the braid will act as an antenna picking up the PC noise and conveying it to the real antena. Alan G3NYK ----- Original Message -----
From: "Mark Pettifor" <mark@...> To: <main@SDR-Radio.groups.io> Sent: Sunday, February 04, 2018 9:04 PM Subject: Re: [SDR-Radio] Best pc design for SDR Based on some older conversations a couple years back on some SDR forum (don't remember which), I've purchased and have had good results with a Lenovo W530 laptop, although I wasn't having good luck with a setup I have up in Michigan at a remote location. I think the antenna wasn't far enough away from the power supply. The feedpoint was about 50 feet away, and I had coax going from there into the shack, so maybe the coax wasn't up to snuff. I have a hard time believing that 50 feet isn't far enough away to minimize or eliminate any radiated noise from the PS. Anyway, the PS is pretty noisy, so it must be kept as far away from the antenna as possible. What I like about the Lenovo is that the sound is excellent, when using headphones. It's almost like there's some kind of "noise cancellation" circuitry being used. Hard to explain, until you hear it. I'm trying to figure out a way to use some 12V DC marine batteries to power the laptop. The laptop needs 19V input, so somehow I need to transform the voltage from the batteries to 19V. I only get about 3 hours max with the "extended life" battery that I got with the laptop when DXing with a SDR attached. Mark |
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Paul Mclaren MM0ZBH
Have a look at some of the mini PC's on the market that you could run headless with an SDR. They run Win 10 and have a decent amount of RAM and SSD so perform well and might well be cheaper than a laptop. Most run on 12v so plenty of scope of powering it from a clean power source rather than a provided bespoke and possible RFI prone laptop PSU. I use a Minix Neo Z83-4 for HF reception but there are other options out there. Regards Paul On 3 Feb 2018, at 11:56, Mike German <mike.german@...> wrote:
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Joe Puma
Are you running SDRC with that Minix Neo Z83, if so how did it perform? I’m looking at some mini PCs and trying to get the best bang for the buck. If it can run SDRC and some decoders or HRD together easily that would be great.
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Joe On Feb 4, 2018, at 5:41 PM, Paul Mclaren MM0ZBH <paul.mcl@...> wrote: |
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Paul Mclaren MM0ZBH
Joe,
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I used to run SDR Server 2.3 with an SDR PlayRSP and it ran fine. Now I run Spyserver for my Airspy HF+ again without issue but plan to try Server 3.0 when released. I have turned off anything in the Windows service stack that wasn't looking essential as well. Regards Paul On 4 Feb 2018, at 23:01, Joe Puma <kd2nfc@...> wrote: |
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Nigel
I'm trying to figure out a way to use some 12V DC marine batteries to
power the laptop. The laptop needs 19V input, so somehow I need to
transform the voltage from the batteries to 19V......
---------------------------------- A DC-DC upconverter is going to need some form of switching supply so from an EMI point of view might leave you back where you started. Why not consider a 24 Volt system with a front end linear charger and then a follow on linear regulator to drop it down to 19 Volts? It won't be particularly efficient, one area where switchers do score, but if noise reduction is your goal perhaps that might be an acceptable compromise. With regards to an appropriate distance to eliminate PSU interference, I have one flourescent light with a modern style electronic ballast that wipes out the relatively local 60KH timing signals from MSF in the UK with a Wellbrook loop antenna anywhere up to say 20 feet away. Another benefit of "progress", flourescent lights have never had a particularly good reputation but the old style choke ballast was never as bad as this! The current mounting position for the loop is at least 50 feet away from that light, perhaps more, and although the effect is less drastic the interference is still quite obvious on any LF SDR. Nigel, GM8PZR |
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Dennis Smith
I used a 100W buck converter for same job when my PSU died (not really a 1 buck though). Several on eBay but maybe worth getting something twice what you need and retrofit asmall fan on the heatsink. I found them for less than £4 before but £10 is still reasonable. Just remember loads of airflow for cooling is a must. Dennis Smith M1DLG On 5 Feb 2018 08:41, "Nigel via Groups.Io" <poldhu1901=aol.com@groups.io> wrote:
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Mike German
Chaps,
There is lots for me to go on here, so thanks for the advice - (but any more would be welcome.) The noise emanates from an HP laptop that I use alongside my relatively quiet Dell Inspiron. I have ferrites on all leads in and out of the offending laptop and using a sniffer the noise at 140 -150 MHz region seemed to come for the between the left hand corner of the keyboard and screen. It doesn’t change when running from battery. I am 99.9% certain it is radiated from the HP. I have an SDRplay RSP2 Pro which comes in it own screened box and an FCDP+ on the Dell. The leads here have ferrites. The noise is highest on the closest antenna and it is difficult to see how the noise gets into the Dell other than that way. But the point of the question was to see look for best options for the HP in the shack. The advice on a full pc in a metal box with attention paid to the psu seems sound. I am considering a mini pc box; I work remote from the Dell and would probably only need screen, keyboard and mouse when setting up. Since the minis have external power supplies I could choose the optimum. I do also have a bench 12V power supply that I use for my pre-amps, noise canceller etc - can the 12 V from this feed a mini pc directly? Also, because the system records 24/7, I would use win 7 which doesn’t force updates and re-starts as win 10 Mike Mike German High Peak Hayfield |
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In olden days we used a mains transformer, rectifier and condensers to produce DC power. Allan G3PIY
From:
main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of Nigel via Groups.Io
I'm trying to figure out a way to use
some 12V DC marine batteries to power the laptop. The laptop needs 19V input,
so somehow I need to transform the voltage from the batteries to 19V...... |
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jj.dijkhuizen@...
Hello to all !
I follow the thread about a pc design. A try-out is upcomming running 2 x pc on a lead-acid rechargeble 12v-7Ah battery. I can recall that heavy-duty Getac-770 and 790 laptops can run on a battery 12Volt. No charging for the internal battery. I will guarding voltage and current and whithout SDRconsole installated. My Dell-Studio 1737 battery voltage is 11.1 Volt, adapter is 19.5 Volt. My Acer-Aspire 7750G battery voltage is 11.1 Volt adapter is 19 Volt 1 battery is charging at the moment.....takes time....and the are old... You will read the results in a time window of 12 hours. sorry for my english writing.... Reg.: jan SWL / NL-13465 |
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jj.dijkhuizen@...
Well, I learned my lesson.
Acer-Aspire will not run on a 12V battery. A stabilizer 19.37 V/2 A is a no go also. The adapter is reated 19V/4.47A !!!! The power source must be a hard one with very low internal resistance.. Thats it..... Reg.: jan SWL-NL13465 |
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What about a 12v and a 6v lead acid battery in series (13.2v + 6.6v =
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19.8v)? Allan G3PIY -----Original Message-----
From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of jj.dijkhuizen@... Sent: 06 February 2018 10:21 To: main@SDR-Radio.groups.io Subject: Re: [SDR-Radio] Best pc design for SDR Well, I learned my lesson. Acer-Aspire will not run on a 12V battery. A stabilizer 19.37 V/2 A is a no go also. The adapter is reated 19V/4.47A !!!! The power source must be a hard one with very low internal resistance.. Thats it..... Reg.: jan SWL-NL13465 |
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Also look up the LT1083 stabiliser (on ebay for example)
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I used one for stabilising 6 volts for the T1154 transmitter valve heaters but they are good up to 35v so 19v should be easy. A 24 volt DC supply plus an LT1083 = 19v/4.47A Allan G3PIY -----Original Message-----
From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of jj.dijkhuizen@... Sent: 06 February 2018 10:21 To: main@SDR-Radio.groups.io Subject: Re: [SDR-Radio] Best pc design for SDR Well, I learned my lesson. Acer-Aspire will not run on a 12V battery. A stabilizer 19.37 V/2 A is a no go also. The adapter is reated 19V/4.47A !!!! The power source must be a hard one with very low internal resistance.. Thats it..... Reg.: jan SWL-NL13465 |
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Augusto <hb9tza@...>
HI folks,
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I was thinking to another solution: I have an old HP that has a power supply of 19V 3A and a battery of 11, 5 V (Li-Ion) so I was thinlking to eliminate the battery and build a 11,5V analogic supply with the needed Amperage. My question, if anybody is able to answer: should I keep the other battery terminal alive? I could build also a resistor net to parse the power at the power supply pins; as there will be no power in the Power Input from AC power supply, I suppose it will not try to charge the battery. I guess the PC internal switchers, having their correct 11,5 DC voltage, will do their job and the PC could be on duty without the need of switching AC inverter generators or switching power supplies, so reducing the RF noise, and being easy to supply the laptop PC from a car battery. Or not? What do you mean? Any opinion on this matter welcome. Thanks. Il 06/02/2018 11:21,
jj.dijkhuizen@... ha scritto:
Well, I learned my lesson. Acer-Aspire will not run on a 12V battery. A stabilizer 19.37 V/2 A is a no go also. The adapter is reated 19V/4.47A !!!! The power source must be a hard one with very low internal resistance.. Thats it..... Reg.: jan SWL-NL13465 . |
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