Any recommendations for a spectrum analyser, say <=10Hz to >=1MHz, maybe USB, hopefully inexpensive, definitely available now, in the UK? Aaronia any good? Not generally very good reviews, but people here may know better. Cheers -- Clive
LF Spectrum Analyser
Started by ●June 27, 2017
Reply by ●June 27, 20172017-06-27
Am 27.06.2017 um 22:25 schrieb Clive Arthur:> Any recommendations for a spectrum analyser, say <=10Hz to >=1MHz, maybe > USB, hopefully inexpensive, definitely available now, in the UK? > > Aaronia any good? Not generally very good reviews, but people here may > know better.A used Agilent 89441A. The IF unit would be enough probably. Available cheaply because people think it is usable only for checking 3G cell phones. cheers, Gerhard
Reply by ●June 28, 20172017-06-28
Clive Arthur <cliveta@nowaytoday.co.uk> writes:> Aaronia any good? Not generally very good reviews, but people here > may know better.Just playing around with one. Performance about ok for my purpose (generator magnet field EMC measurements), but the software feels uncertain at least on Mac. As an example, I'm having hard time to keep the unit as dBuV while changing span or some other parameters. I'll compare with HP 3585A when I get back from the gig. -- mikko
Reply by ●June 28, 20172017-06-28
On Tuesday, June 27, 2017 at 4:26:01 PM UTC-4, Clive Arthur wrote:> Any recommendations for a spectrum analyser, say <=10Hz to >=1MHz, maybe > USB, hopefully inexpensive, definitely available now, in the UK? > > Aaronia any good? Not generally very good reviews, but people here may > know better. > > Cheers > -- > CliveWhat's low cost? I've been lusting after a Rigol SA. I see there is now a low end (100 kHz to 500 MHz) one ~ $700.00, but I would like a DSA815 with TG. There seems to be a divide in the SA market at ~100 kHz. With 'audio' SA's from milli-Hertz to 100kHz, and then the RF stuff. I use the FFT on my 'scope as a low end SA, but it's not very good at zooming in on one limited frequency window. What are you doing? George H.
Reply by ●June 28, 20172017-06-28
On Wed, 28 Jun 2017 06:06:36 -0700 (PDT), George Herold <gherold@teachspin.com> wrote:>On Tuesday, June 27, 2017 at 4:26:01 PM UTC-4, Clive Arthur wrote: >> Any recommendations for a spectrum analyser, say <=10Hz to >=1MHz, maybe >> USB, hopefully inexpensive, definitely available now, in the UK? >> >> Aaronia any good? Not generally very good reviews, but people here may >> know better. >> >> Cheers >> -- >> Clive > >What's low cost? I've been lusting after a Rigol SA. I see there is now a >low end (100 kHz to 500 MHz) one ~ $700.00, but I would like a DSA815 with TG. There seems to be a divide in the SA market at ~100 kHz. >With 'audio' SA's from milli-Hertz to 100kHz, and then the RF stuff. > >I use the FFT on my 'scope as a low end SA, but it's not very good at >zooming in on one limited frequency window. What are you doing? > >George H.Do these 100 kHz 'audio' SAs have proper S&H at input ? In that case use a local oscillator (LO) to mix up a frequency segment of interest to a convenient intermediate frequency say 45 MHz. Using a 100 kHz roofing filter to limit the spectrum to 45.0 to 45.1 MHz and feed it to the 100 kHz audio SA. To select a different 100 kHz segment,just step he LO in 100 kHz steps. Due to the big frequency step, even a PLL can be used as the LO, without introducing too much phase noise. Search for "waterfall display" and WebSDR. These often use an I/Q (Zero IF) front end with cheap "audio" A/D converters.
Reply by ●June 28, 20172017-06-28
On 2017-06-27 13:25, Clive Arthur wrote:> Any recommendations for a spectrum analyser, say <=10Hz to >=1MHz, maybe > USB, hopefully inexpensive, definitely available now, in the UK? > > Aaronia any good? Not generally very good reviews, but people here may > know better. >I have a Signalhound. https://signalhound.com/products/usb-sa44b/ Supposedly it goes down to 1Hz but I never used it much below 150kHz. So far it has found all the stuff I was looking for but you have to keep in mind that these budget-level analyzers are in essence glorified software-defined radios (SDR). They convert down and analyze the spctrum in slivers, then piece together the results in software. This has two disadvantages, usually no good image rejection (it's done in software) and they cannot handle pulsed signals very well. The main reason I bought it was its portability. Also, be very careful with the input amplitude because at 10Hz you can't reasonably protect that by AC coupling. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●June 28, 20172017-06-28
On Wednesday, June 28, 2017 at 10:32:57 AM UTC-4, upsid...@downunder.com wrote:> On Wed, 28 Jun 2017 06:06:36 -0700 (PDT), George Herold > <gherold@teachspin.com> wrote: > > >On Tuesday, June 27, 2017 at 4:26:01 PM UTC-4, Clive Arthur wrote: > >> Any recommendations for a spectrum analyser, say <=10Hz to >=1MHz, maybe > >> USB, hopefully inexpensive, definitely available now, in the UK? > >> > >> Aaronia any good? Not generally very good reviews, but people here may > >> know better. > >> > >> Cheers > >> -- > >> Clive > > > >What's low cost? I've been lusting after a Rigol SA. I see there is now a > >low end (100 kHz to 500 MHz) one ~ $700.00, but I would like a DSA815 with TG. There seems to be a divide in the SA market at ~100 kHz. > >With 'audio' SA's from milli-Hertz to 100kHz, and then the RF stuff. > > > >I use the FFT on my 'scope as a low end SA, but it's not very good at > >zooming in on one limited frequency window. What are you doing? > > > >George H. > > Do these 100 kHz 'audio' SAs have proper S&H at input ?Sample and Hold? I don't think so. We've got an SRS770. I've done the mixing trick to look at somewhat higher frequencies. (a few MHz.) But not the best filtering, so all sorts of aliasing (if that's the right term) of stuff into the 100 kHz window. (I'd figure out what is what by changing the LO and seeing how things moved.. not the best.) George H.> > In that case use a local oscillator (LO) to mix up a frequency segment > of interest to a convenient intermediate frequency say 45 MHz. Using a > 100 kHz roofing filter to limit the spectrum to 45.0 to 45.1 MHz and > feed it to the 100 kHz audio SA. > > To select a different 100 kHz segment,just step he LO in 100 kHz > steps. Due to the big frequency step, even a PLL can be used as the > LO, without introducing too much phase noise. > > Search for "waterfall display" and WebSDR. These often use an I/Q > (Zero IF) front end with cheap "audio" A/D converters.
Reply by ●June 29, 20172017-06-29
On 27/06/2017 21:25, Clive Arthur wrote:> Any recommendations for a spectrum analyser, say <=10Hz to >=1MHz, maybe > USB, hopefully inexpensive, definitely available now, in the UK? > > Aaronia any good? Not generally very good reviews, but people here may > know better. >Any experience of this... https://analogdiscovery.com/ 14 bit ADC, inexpensive, would need hiding in a box. Maybe even buy a cheap Chinese USB scope just for the enclosure. Cheers -- Clive
Reply by ●June 29, 20172017-06-29
On Wed, 28 Jun 2017 07:49:56 -0700 (PDT), George Herold <gherold@teachspin.com> wrote:>On Wednesday, June 28, 2017 at 10:32:57 AM UTC-4, upsid...@downunder.com wrote: >> On Wed, 28 Jun 2017 06:06:36 -0700 (PDT), George Herold >> <gherold@teachspin.com> wrote: >> >> >On Tuesday, June 27, 2017 at 4:26:01 PM UTC-4, Clive Arthur wrote: >> >> Any recommendations for a spectrum analyser, say <=10Hz to >=1MHz, maybe >> >> USB, hopefully inexpensive, definitely available now, in the UK? >> >> >> >> Aaronia any good? Not generally very good reviews, but people here may >> >> know better. >> >> >> >> Cheers >> >> -- >> >> Clive >> > >> >What's low cost? I've been lusting after a Rigol SA. I see there is now a >> >low end (100 kHz to 500 MHz) one ~ $700.00, but I would like a DSA815 with TG. There seems to be a divide in the SA market at ~100 kHz. >> >With 'audio' SA's from milli-Hertz to 100kHz, and then the RF stuff. >> > >> >I use the FFT on my 'scope as a low end SA, but it's not very good at >> >zooming in on one limited frequency window. What are you doing? >> > >> >George H. >> >> Do these 100 kHz 'audio' SAs have proper S&H at input ? >Sample and Hold? I don't think so. We've got an SRS770.The reason that I was asking is that while in traditional ADCs with S&H can easily handle _bandlimited_ high frequency signal by decimation, the only critical parameter is _transition_ time between sample and hold state. Thus, if the transition time is about 1 ns, quite high frequencies can be sampled without too much aperture error from say a band limited 50 MHz IF signal. But how about delta/sigma converters, can they handle bandlimited high frequency signals and properly decimate or is a S&H stage needed in between ?>I've done the mixing trick to look at somewhat higher frequencies. >(a few MHz.) But not the best filtering, so all sorts of >aliasing (if that's the right term) of stuff into the 100 kHz window. >(I'd figure out what is what by changing the LO and seeing how things >moved.. not the best.)Using some common intermediate frequencies, such as 455 kHz, 10.7 MHz or 45 MHz and there is a huge number of commercial ceramic or crystal filters with a few kHz to at least 300 kHz bandwidth available. These filters will help getting away with most of the aliasis. For a more modern approach, take a look at www.websdr.org and try out some of these receiving station. These typically digitize a whole amateur radio band, producing a spectrum and waterfall display. In addition, several clients over the internet can connect to this station, independently tune around the digitized band, perform demodulation (CW, SSB, AM or FM) and transfer the audio over the internet to individual clients. Of course SSB "demodulation" is just a frequency transfer, so the end user could do any analysis to that "audio" bandwidth. Most of those WebSDR stations are simple PCs with a stereo 192 kHz sampling rate sound card. Some use I/Q mixers driving the left and right audio channel. The local oscillator can be a sin/cos DDS or simply a crystal with 90 phase shifter. All the rest is done in PC software. Try one of those. I still do not understand how somebody can sell 100 kHz SAs (SRS770) starting from USD5000 :-)
Reply by ●June 29, 20172017-06-29
On Thursday, June 29, 2017 at 6:19:42 AM UTC-4, upsid...@downunder.com wrote:> On Wed, 28 Jun 2017 07:49:56 -0700 (PDT), George Herold > <gherold@teachspin.com> wrote: > > >On Wednesday, June 28, 2017 at 10:32:57 AM UTC-4, upsid...@downunder.com wrote: > >> On Wed, 28 Jun 2017 06:06:36 -0700 (PDT), George Herold > >> <gherold@teachspin.com> wrote: > >> > >> >On Tuesday, June 27, 2017 at 4:26:01 PM UTC-4, Clive Arthur wrote: > >> >> Any recommendations for a spectrum analyser, say <=10Hz to >=1MHz, maybe > >> >> USB, hopefully inexpensive, definitely available now, in the UK? > >> >> > >> >> Aaronia any good? Not generally very good reviews, but people here may > >> >> know better. > >> >> > >> >> Cheers > >> >> -- > >> >> Clive > >> > > >> >What's low cost? I've been lusting after a Rigol SA. I see there is now a > >> >low end (100 kHz to 500 MHz) one ~ $700.00, but I would like a DSA815 with TG. There seems to be a divide in the SA market at ~100 kHz. > >> >With 'audio' SA's from milli-Hertz to 100kHz, and then the RF stuff. > >> > > >> >I use the FFT on my 'scope as a low end SA, but it's not very good at > >> >zooming in on one limited frequency window. What are you doing? > >> > > >> >George H. > >> > >> Do these 100 kHz 'audio' SAs have proper S&H at input ? > >Sample and Hold? I don't think so. We've got an SRS770. > > The reason that I was asking is that while in traditional ADCs with > S&H can easily handle _bandlimited_ high frequency signal by > decimation, the only critical parameter is _transition_ time between > sample and hold state. Thus, if the transition time is about 1 ns, > quite high frequencies can be sampled without too much aperture error > from say a band limited 50 MHz IF signal. > > But how about delta/sigma converters, can they handle bandlimited > high frequency signals and properly decimate or is a S&H stage needed > in between ? > > >I've done the mixing trick to look at somewhat higher frequencies. > >(a few MHz.) But not the best filtering, so all sorts of > >aliasing (if that's the right term) of stuff into the 100 kHz window. > >(I'd figure out what is what by changing the LO and seeing how things > >moved.. not the best.) > > Using some common intermediate frequencies, such as 455 kHz, 10.7 MHz > or 45 MHz and there is a huge number of commercial ceramic or crystal > filters with a few kHz to at least 300 kHz bandwidth available. These > filters will help getting away with most of the aliasis. > > For a more modern approach, take a look at www.websdr.org and try out > some of these receiving station. These typically digitize a whole > amateur radio band, producing a spectrum and waterfall display. > > In addition, several clients over the internet can connect to this > station, independently tune around the digitized band, perform > demodulation (CW, SSB, AM or FM) and transfer the audio over the > internet to individual clients. Of course SSB "demodulation" is just a > frequency transfer, so the end user could do any analysis to that > "audio" bandwidth. > > Most of those WebSDR stations are simple PCs with a stereo 192 kHz > sampling rate sound card. Some use I/Q mixers driving the left and > right audio channel. The local oscillator can be a sin/cos DDS or > simply a crystal with 90 phase shifter. > > All the rest is done in PC software. > > Try one of those.OK Thanks... I don't know anything about SDR. (except in theory) I would mostly want a box that I could turn knobs and get a spectrum.> > I still do not understand how somebody can sell 100 kHz SAs (SRS770) > starting from USD5000 :-)Well that's their old (1980's) version. It's got a decent low noise front end. They make a newer one, http://www.thinksrs.com/products/SR1.htm ~$10k. Audio market. :^) George H.
