On 06/29/2017 06:19 AM, upsidedown@downunder.com wrote:> I still do not understand how somebody can sell 100 kHz SAs (SRS770) > starting from USD5000 :-)I have an HP 35665A that I love. I paid $350 for it about 8 or 9 years ago, and it works flawlessly. They're very good for tuning analogue control loops, for instance, or for measuring the transfer function of some slow plant such as a TEC/thermistor or voice coil/LVDT. It also has swept sine and Gaussian white noise sources and a bunch of other useful functions. Plus it runs good old Rocky Mountain Basic, so you can use it to control other instruments. (Shades of grad school.) I got the All Options ROM from GLK Instruments for $50, which unlocks all the built-in goodies. They have to customize it for your unit's serial number. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
LF Spectrum Analyser
Started by ●June 27, 2017
Reply by ●June 29, 20172017-06-29
Reply by ●June 29, 20172017-06-29
On Tuesday, June 27, 2017 at 9:26:01 PM UTC+1, 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 > -- > CliveTry www.analogarts.com Prof78
Reply by ●June 29, 20172017-06-29
On 29/06/2017 15:03, Phil Hobbs wrote:> On 06/29/2017 06:19 AM, upsidedown@downunder.com wrote: >> I still do not understand how somebody can sell 100 kHz SAs (SRS770) >> starting from USD5000 :-) > > I have an HP 35665A that I love. I paid $350 for it about 8 or 9 years > ago, and it works flawlessly. > > They're very good for tuning analogue control loops, for instance, or > for measuring the transfer function of some slow plant such as a > TEC/thermistor or voice coil/LVDT. > > It also has swept sine and Gaussian white noise sources and a bunch of > other useful functions. Plus it runs good old Rocky Mountain Basic, so > you can use it to control other instruments. (Shades of grad school.) > > I got the All Options ROM from GLK Instruments for $50, which unlocks > all the built-in goodies. They have to customize it for your unit's > serial number. > > Cheers > > Phil Hobbs >I'd be loathed to pay anyone $50 for 30 seconds of their time programming a 50c part. I upgraded mine thanks to the instructions shared by George. Hi all, This topic about the eeprom in the HP 35665A seems to be quiet for sometime. I thought that I would share my recent findings about the 35665A options. A few months ago, I purchased a like new 35665A with all documentation except the service manual. It had only one option ANA. Unfortunately, I have not been able to locate the service manual or options disks and there is no support from Agilent. After some detective work and from the post #21350 and others, I was able to active all of the options. The bits to activate options 1D4, 1D3, 1D2, 1D1, 1D0, 1C2, and 1C1 are stored at hex address locations 23h, 24h, 25h, 26h, 27h, 28h, 29h, respectively. To active all options or any option, fill the address location(s) with 76h. Here is the eeprom hex dump from my instrument: 0000: 00 13 20 5D 04 05 06 00 08 09 48 50 33 35 36 36 .. ]......HP3566 0010: 35 41 20 20 33 34 34 35 41 30 32 36 36 36 1E 1F 5A 3445A02666.. 0020: 20 21 00 76 76 76 76 76 76 19 2A 2B 2C 2D 2E 2F !.vvvvvv.*+,-./ 0030: 48 45 57 4C 45 54 54 2D 50 41 43 4B 41 52 44 20 HEWLETT-PACKARD 0040: 33 35 36 36 35 41 20 44 59 4E 41 4D 49 43 20 20 35665A DYNAMIC 0050: 53 49 47 4E 41 4C 20 41 4E 41 4C 59 5A 45 52 20 SIGNAL ANALYZER 0060: 60 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F `abcdefghijklmno 0070: 70 71 72 73 74 75 41 77 78 79 7A 7B 7C 4D 48 99 pqrstuAwxyz{|MH. I will also upload the binary file. With a hex editor, you can edit the binary file and put in your instrument's serial number in place of 3445A02666 although this is not necessary. Remember that options 1C2 and ANA are mutually exclusive. Also, the 85C72 eeproms are obsolete (and expensive if you order from IC dealer who specializes in obselete ICs). Use Microchip's 24C01 eeprom - they are $0.29 from Mouser. They are equivalent and work fine in the 35665A. Also, you might want to replace the lithium battery (B200 on the main board) while you have the instrument open. Regards, George
Reply by ●June 29, 20172017-06-29
On 06/29/2017 12:37 PM, JM wrote:> On 29/06/2017 15:03, Phil Hobbs wrote: >> On 06/29/2017 06:19 AM, upsidedown@downunder.com wrote: >>> I still do not understand how somebody can sell 100 kHz SAs (SRS770) >>> starting from USD5000 :-) >> >> I have an HP 35665A that I love. I paid $350 for it about 8 or 9 years >> ago, and it works flawlessly. >> >> They're very good for tuning analogue control loops, for instance, or >> for measuring the transfer function of some slow plant such as a >> TEC/thermistor or voice coil/LVDT. >> >> It also has swept sine and Gaussian white noise sources and a bunch of >> other useful functions. Plus it runs good old Rocky Mountain Basic, so >> you can use it to control other instruments. (Shades of grad school.) >> >> I got the All Options ROM from GLK Instruments for $50, which unlocks >> all the built-in goodies. They have to customize it for your unit's >> serial number. >> >> Cheers >> >> Phil Hobbs >> > > I'd be loathed to pay anyone $50 for 30 seconds of their time > programming a 50c part. > > I upgraded mine thanks to the instructions shared by George.You're just cheap, is all. $50 to a public benefactor like that is money very sell spent. Thanks for sharing the instructions. Cheers Phil Hobbs> > Hi all, > This topic about the eeprom in the HP 35665A seems to be quiet for > sometime. I > thought that I would share my recent findings about the 35665A options. > A few > months ago, I purchased a like new 35665A with all documentation except the > service manual. It had only one option ANA. Unfortunately, I have not > been able > to locate the service manual or options disks and there is no support from > Agilent. After some detective work and from the post #21350 and others, > I was > able to active all of the options. > > The bits to activate options 1D4, 1D3, 1D2, 1D1, 1D0, 1C2, and 1C1 are > stored at > hex address locations 23h, 24h, 25h, 26h, 27h, 28h, 29h, respectively. > To active > all options or any option, fill the address location(s) with 76h. Here > is the > eeprom hex dump from my instrument: > > 0000: 00 13 20 5D 04 05 06 00 08 09 48 50 33 35 36 36 .. ]......HP3566 > 0010: 35 41 20 20 33 34 34 35 41 30 32 36 36 36 1E 1F 5A 3445A02666.. > 0020: 20 21 00 76 76 76 76 76 76 19 2A 2B 2C 2D 2E 2F !.vvvvvv.*+,-./ > 0030: 48 45 57 4C 45 54 54 2D 50 41 43 4B 41 52 44 20 HEWLETT-PACKARD > 0040: 33 35 36 36 35 41 20 44 59 4E 41 4D 49 43 20 20 35665A DYNAMIC > 0050: 53 49 47 4E 41 4C 20 41 4E 41 4C 59 5A 45 52 20 SIGNAL ANALYZER > 0060: 60 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F `abcdefghijklmno > 0070: 70 71 72 73 74 75 41 77 78 79 7A 7B 7C 4D 48 99 pqrstuAwxyz{|MH. > > I will also upload the binary file. With a hex editor, you can edit the > binary > file and put in your instrument's serial number in place of 3445A02666 > although > this is not necessary. Remember that options 1C2 and ANA are mutually > exclusive. > > Also, the 85C72 eeproms are obsolete (and expensive if you order from IC > dealer > who specializes in obselete ICs). Use Microchip's 24C01 eeprom - they > are $0.29 > from Mouser. They are equivalent and work fine in the 35665A. Also, you > might > want to replace the lithium battery (B200 on the main board) while you > have the > instrument open. > > Regards, George-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●June 30, 20172017-06-30
On 29/06/17 20:19, upsidedown@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.Very few, in fact. There's a whole range of types, your review was very limited.>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. > I still do not understand how somebody can sell 100 kHz SAs (SRS770) > starting from USD5000 :-)Mostly it's dynamic range, and image rejection. Zero-IF converters get a lot of LO2 feedthrough. Low-IF still has a number of image problems unless you have very good front-end filters (and few SDRs do). 8-bit converters (like in RTL-SDR) might be adequate to receive digital TV, but nearly useless as an SA. Really wide-band front-ends have massive noise problems that makes wide dynamic range a near impossibility. In short, the better hobbyist-grade SDRs are good to perhaps 40dB, whereas pro equipment goes beyond 70dB. The hobbyist community seems blissfully unaware of many of these problems, because they don't own and perhaps have never even used pro-quality instruments, and don't understand why they are so complicated, with cavity resonator filters and banks of switchable or electronically-tuned filters. Clifford Heath.
Reply by ●July 1, 20172017-07-01
On Fri, 30 Jun 2017 17:09:50 +1000, Clifford Heath <no.spam@please.net> wrote:>On 29/06/17 20:19, upsidedown@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. > >Very few, in fact. There's a whole range of types, your review >was very limited. > >>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. >> I still do not understand how somebody can sell 100 kHz SAs (SRS770) >> starting from USD5000 :-) > >Mostly it's dynamic range, and image rejection. > >Zero-IF converters get a lot of LO2 feedthrough. > >Low-IF still has a number of image problems unless you have >very good front-end filters (and few SDRs do). > >8-bit converters (like in RTL-SDR) might be adequate to >receive digital TV, but nearly useless as an SA. > >Really wide-band front-ends have massive noise problems >that makes wide dynamic range a near impossibility. > >In short, the better hobbyist-grade SDRs are good to >perhaps 40dB, whereas pro equipment goes beyond 70dB.Listen to http://websdr.ewi.utwente.nl:8901/ with 16 bit sampling of 0 to 29 MHz. Use "View Spectrum" to get the traditional spectrum display instead of waterfall display. Left click on the frequency scale to change frequency. Unfortunately the receiver is on a campus with high background noise and of course there is a lot of band noise on HF and especially on MF/LF, so the true potential of the ADC is hard to determine. The strongest signal seems to be a nearby pager at 27 MHz at about 0 dBm. At upper HF the background noise is about -100 dBm in 3 kHz bandwidth. To me, this works surprisingly well for its intended purpose, but of course, this is not a calibrated test instrument.> >The hobbyist community seems blissfully unaware of many of >these problems, because they don't own and perhaps have never >even used pro-quality instruments, and don't understand why >they are so complicated, with cavity resonator filters and >banks of switchable or electronically-tuned filters.The problem is that in past decades quite complex structures were needed for spectrum analyzers and general coverage receivers (such as multiple PLLs). Today, when good components are available, such as NCOs, DACs and ADCs the same performance can be achieved with less complexity and hence less cost.> >Clifford Heath.
Reply by ●July 1, 20172017-07-01
On 02/07/17 07:14, upsidedown@downunder.com wrote:> On Fri, 30 Jun 2017 17:09:50 +1000, Clifford Heath > <no.spam@please.net> wrote: >> The hobbyist community seems blissfully unaware of many of >> these problems, because they don't own and perhaps have never >> even used pro-quality instruments, and don't understand why >> they are so complicated, with cavity resonator filters and >> banks of switchable or electronically-tuned filters. > > The problem is that in past decades quite complex structures were > needed for spectrum analyzers and general coverage receivers (such as > multiple PLLs). Today, when good components are available, such as > NCOs, DACs and ADCs the same performance can be achieved with less > complexity and hence less cost.Not the same performance. Adequate for many tasks, but no way the same. The best wide-band SDRs have big banks of RF filters, and they're still not as good as a proper communications receiver. Good enough to make pretty waterfall displays, but no way the same.
Reply by ●July 1, 20172017-07-01
On Sunday, July 2, 2017 at 1:08:15 AM UTC+2, Clifford Heath wrote:> On 02/07/17 07:14, upsidedown@downunder.com wrote: > > On Fri, 30 Jun 2017 17:09:50 +1000, Clifford Heath > > <no.spam@please.net> wrote: > >> The hobbyist community seems blissfully unaware of many of > >> these problems, because they don't own and perhaps have never > >> even used pro-quality instruments, and don't understand why > >> they are so complicated, with cavity resonator filters and > >> banks of switchable or electronically-tuned filters. > > > > The problem is that in past decades quite complex structures were > > needed for spectrum analyzers and general coverage receivers (such as > > multiple PLLs). Today, when good components are available, such as > > NCOs, DACs and ADCs the same performance can be achieved with less > > complexity and hence less cost. > > Not the same performance. Adequate for many tasks, but no way the same. > The best wide-band SDRs have big banks of RF filters, and they're > still not as good as a proper communications receiver. Good enough > to make pretty waterfall displays, but no way the same.For low frequency high res I have a National Instrument DAQ 24 bit aquisition unit: http://www.ni.com/datasheet/pdf/en/ds-324 And a cheap SW I got for 100 USD that does all sorts of tricks I can dig up signals buried 100dB below a carrier I actually have one unit for sale for highest bidder 😀 Cheers Klaus
Reply by ●July 2, 20172017-07-02
On Sun, 2 Jul 2017 09:08:05 +1000, Clifford Heath <no.spam@please.net> wrote:>On 02/07/17 07:14, upsidedown@downunder.com wrote: >> On Fri, 30 Jun 2017 17:09:50 +1000, Clifford Heath >> <no.spam@please.net> wrote: >>> The hobbyist community seems blissfully unaware of many of >>> these problems, because they don't own and perhaps have never >>> even used pro-quality instruments, and don't understand why >>> they are so complicated, with cavity resonator filters and >>> banks of switchable or electronically-tuned filters. >> >> The problem is that in past decades quite complex structures were >> needed for spectrum analyzers and general coverage receivers (such as >> multiple PLLs). Today, when good components are available, such as >> NCOs, DACs and ADCs the same performance can be achieved with less >> complexity and hence less cost. > >Not the same performance. Adequate for many tasks, but no way the same. >The best wide-band SDRs have big banks of RF filters, and they're >still not as good as a proper communications receiver. Good enough >to make pretty waterfall displays, but no way the same.The weakest point in both SA as well as general coverage receivers and scanners is the mixer.The situation can be somewhat helped by using special mixer structures and/or using a lot of power (not possible in a portable device). In addition, if you are driving a mixer with a square wave, there will be mixing products between the odd harmonics of the LO and input spectrum at the IF distance of the odd harmonics of the LO. For this reason, octave filters are used to keep frequencies close to the 3rd harmonics (and higher) out of the mixer. For a SA with 1 kHz to 3 GHz range, you will need more than 20 octave filters to cover the range. The good thing is that you can attenuate each octave separately and fix the corresponding attenuation in the display. In fact suboctave front end filters might be helpful to filter out second order mixing products of two strong input signals at the lower end of the octave, which would fall on the upper end of the octave. However if the upper frequency requirement is more modest (say HF/VHF), you could get away with the problematic mixer and run the signal directly into the ADC. It should be noted that a 16 bit ADC the theoretical weak signal resolution is 97 dB, there are always going to be band and front end noise, which work as dither, making it possible to resolve signals well below 100 dB FSD. While the problematic mixing has been used for decades, the performance of ADCs will constantly increase, moving the practical dividing line to higher and higher frequencies.
Reply by ●July 3, 20172017-07-03
On 02/07/17 16:46, upsidedown@downunder.com wrote:> On Sun, 2 Jul 2017 09:08:05 +1000, Clifford Heath <no.spam@please.net> > wrote: >> On 02/07/17 07:14, upsidedown@downunder.com wrote: >>> On Fri, 30 Jun 2017 17:09:50 +1000, Clifford Heath >>> <no.spam@please.net> wrote: >>>> The hobbyist community seems blissfully unaware of many of >>>> these problems, >>> The problem is that in past decades quite complex structures were >>> needed for spectrum analyzers and general coverage receivers (such as >>> multiple PLLs). Today, when good components are available, such as >>> NCOs, DACs and ADCs the same performance can be achieved with less >>> complexity and hence less cost. >> Not the same performance. Adequate for many tasks, but no way the same. > The weakest point in both SA as well as general coverage receivers and > scanners is the mixer.Mixers are non-linear devices. Even a perfect mixer will still have the same image problems that plague real receivers.> In addition, if you are driving a mixer with a square wave, there will > be mixing products between the odd harmonics of the LO and input > spectrum at the IF distance of the odd harmonics of the LO. For this > reason, octave filters are used to keep frequencies close to the 3rd > harmonics (and higher) out of the mixer.Zero-IF receivers are also afflicted by 2LO, not just 3LO, because the frequencies "fold around" zero. There's quite a good review of available devices in the slides here (though these still pass over some of the problems): <http://microhams.blob.core.windows.net/content/2017/03/RTL-SDR-dongle.pdf> Clifford Heath.
