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Author Topic: SDR Radio Suggestions?  (Read 54063 times)
KE5JPP
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« Reply #75 on: July 05, 2011, 02:36:02 PM »

Do you just go around all the SDR groups being a troll? Do you even own an SDR. Every message I see from you is talking about not buying this one or not buying this other one because this and that. And not liking SDR-Radio because it is not free and this and that?

Pieter, N4IP
Quote
If you did not use your ears, what did you use? Your finger? a voltmeter? a light bulb?

Pieter, N4IP
Quote
Just because you don't have the BW, it does not mean that it can't be done.

Pieter N4IP

You need to calm down a bit and stop frantically posting nonsense over and over again and making an A** out of yourself.  If you had searched around some more for statements in your attempts to indict me, you would have seen that the manufacturer of Perseus contacted me and addressed all my concerns.  He calmly and politely explained each issue even though English was not his first language. He explained that he was having a bad day and was frustrated when he responded to the other messages that I was referring to.  I purchased a Perseus and I am generally a happy customer.  I have also owned a SDR-IQ, amongst others.  I see that you are employed by RF Space.  I have found that in my dealings with SDR manufacturers, they almost universally take negative criticisms personally as if I had insulted their child.  I only expect manufacturers to be polite when legitimate questions are asked.  It is very concerning when an employee of a company comes out and throws mud at a once potential customer over negative criticism like you are doing here.

If the NetSDR that I had on loan and I tested is indeed defective as you claim, I will pass this message on to my friend so he can arrange for a repair.  As for your comment about my Internet connection, it is provided by my ISP and it is a very good, high speed connection.  Unfortunately, my ISP does not control all of the Internet and cannot guarantee the high speed reliable access between any two Internet users.  So your argument that my Internet connection has something to do with the viability of passing raw, unprocessed IQ data over the Internet has no credibility.  Those raw, unprocessed IQ data packets still have to pass via different, uncontrollable by the end user, segments of the Internet with wildly varying latency and reliably of delivery.  The only users who are going to reliably pass raw unprocessed IQ data are those on local network connections, not the Internet.

Gene


Gene,

I am not posting nonsense. If you are going to claim something, it is in the best interest of the group to see some data. You do not make this available or say how you performed the tests. That's all.

Pieter, N4IP



Pieter,

Please describe exactly what test equipment, detailed test conditions, and the detailed test procedures that you used to determine the performance CLAIMS that you make for the NetSDR on the RF Space webpage and in this forum.  If you are going to claim something, it is in the best interest of the group to see some data.  You do not make this available or say how you performed the tests.  If I am to be held to such a high standard when I make test claims then YOU as the manufacturer should be at least held to the same high standard also.

Gene

We'll let the third parties like SM5BSZ that know what phase noise actually is publish their findings. http://www.sm5bsz.com/lir/sdrcmp/bdr/bdr.htm



Does the SDR-IP use the same oscillator as the NetSDR? The link you provided does not have any data for the NetSDR.

Gene
« Last Edit: July 05, 2011, 02:41:45 PM by KE5JPP » Logged
WB6RQN
Member

Posts: 484




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« Reply #76 on: July 06, 2011, 11:29:06 AM »

Now 1 gig or 10 gig Ethernet on a local network would open a lot of wide-band applications and is an exciting possibility. It would be worth the additional $500.  I just don't see trying to push raw, unprocessed IQ data over the internet.

I guess it depends on whether you have filtered and decimated first to reduce the bit-rate. I can see sending one or more channels of I/Q data over the internet for remote processing. But I agree that the raw I/Q output of a wideband receiver is likely to have to stay on the local network where there is ample capacity.

73 de Brian, WB6RQN/J79BPL
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N4IP
Member

Posts: 16


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« Reply #77 on: July 06, 2011, 03:07:32 PM »

Do you just go around all the SDR groups being a troll? Do you even own an SDR. Every message I see from you is talking about not buying this one or not buying this other one because this and that. And not liking SDR-Radio because it is not free and this and that?

Pieter, N4IP
Quote
If you did not use your ears, what did you use? Your finger? a voltmeter? a light bulb?

Pieter, N4IP
Quote
Just because you don't have the BW, it does not mean that it can't be done.

Pieter N4IP

You need to calm down a bit and stop frantically posting nonsense over and over again and making an A** out of yourself.  If you had searched around some more for statements in your attempts to indict me, you would have seen that the manufacturer of Perseus contacted me and addressed all my concerns.  He calmly and politely explained each issue even though English was not his first language. He explained that he was having a bad day and was frustrated when he responded to the other messages that I was referring to.  I purchased a Perseus and I am generally a happy customer.  I have also owned a SDR-IQ, amongst others.  I see that you are employed by RF Space.  I have found that in my dealings with SDR manufacturers, they almost universally take negative criticisms personally as if I had insulted their child.  I only expect manufacturers to be polite when legitimate questions are asked.  It is very concerning when an employee of a company comes out and throws mud at a once potential customer over negative criticism like you are doing here.

If the NetSDR that I had on loan and I tested is indeed defective as you claim, I will pass this message on to my friend so he can arrange for a repair.  As for your comment about my Internet connection, it is provided by my ISP and it is a very good, high speed connection.  Unfortunately, my ISP does not control all of the Internet and cannot guarantee the high speed reliable access between any two Internet users.  So your argument that my Internet connection has something to do with the viability of passing raw, unprocessed IQ data over the Internet has no credibility.  Those raw, unprocessed IQ data packets still have to pass via different, uncontrollable by the end user, segments of the Internet with wildly varying latency and reliably of delivery.  The only users who are going to reliably pass raw unprocessed IQ data are those on local network connections, not the Internet.

Gene


Gene,

I am not posting nonsense. If you are going to claim something, it is in the best interest of the group to see some data. You do not make this available or say how you performed the tests. That's all.

Pieter, N4IP



Pieter,

Please describe exactly what test equipment, detailed test conditions, and the detailed test procedures that you used to determine the performance CLAIMS that you make for the NetSDR on the RF Space webpage and in this forum.  If you are going to claim something, it is in the best interest of the group to see some data.  You do not make this available or say how you performed the tests.  If I am to be held to such a high standard when I make test claims then YOU as the manufacturer should be at least held to the same high standard also.

Gene

We'll let the third parties like SM5BSZ that know what phase noise actually is publish their findings. http://www.sm5bsz.com/lir/sdrcmp/bdr/bdr.htm



Does the SDR-IP use the same oscillator as the NetSDR? The link you provided does not have any data for the NetSDR.

Gene


The NetSDR and SDR-IP both use the same ADC and oscillator. The oscillator they use is the same as the Perseus. Both the NetSDR and SDR-IP have the option of adding a reflock unit with a really good oscillator (but pricey). We are working on a lower cost alternative using a very good VCXO.

Pieter
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N4IP
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Posts: 16


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« Reply #78 on: July 06, 2011, 03:13:24 PM »

Now 1 gig or 10 gig Ethernet on a local network would open a lot of wide-band applications and is an exciting possibility. It would be worth the additional $500.  I just don't see trying to push raw, unprocessed IQ data over the internet.

I guess it depends on whether you have filtered and decimated first to reduce the bit-rate. I can see sending one or more channels of I/Q data over the internet for remote processing. But I agree that the raw I/Q output of a wideband receiver is likely to have to stay on the local network where there is ample capacity.

73 de Brian, WB6RQN/J79BPL


Brian,

Most people will not attempt to send raw data over the internet. I have tried it with narrow bandwidths and it works fine. The real convenience is being able to put the radio on the intranet where any computer in the house or business can see it. I have a setup with 8 receivers for an array and they are all connected to a 16 port gigE switch. Then I have a single cable with 8 radios on it. There are customers that connect then to $100 media converters and can now run fiber to the unit over long distances. For people that are happy with their 10 foot USB connection, it is definitely not worth the extra expense. We are going to eventually go all Ethernet, because customers like it.

Pieter
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N4IP
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Posts: 16


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« Reply #79 on: July 06, 2011, 08:32:26 PM »


[/quote]

This discussion has been interesting but I wish you fellows would learn to not Quote the whole post as it makes your post difficult to read. Just quote a little....

Since Pieter says it is not worth the extra $$ can I assume this is not a SDR that a hamradio Op should buy? I started this thread and looked at the Netsdr and came to the conclusion it was way too much $$$ compared to the competition.

I am interested in an SDR and have looked at many. I am still sitting on the sideline however, as I can see no real value in most of the SDR's. Their prices make Flexradio look cheap....

Stan K9IUQ

[/quote]

Stan,  I am not saying that it is not worth it. You either need the network connectivity or you don't. You also get some additional functionality that might not be available in other receivers like frequency locking, options of internal converters, choice of software, etc. The customer makes the decision of whether it is worth it or not. Regards, Pieter   (Sorry about the quoting)
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K0OD
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Posts: 2521




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« Reply #80 on: July 06, 2011, 08:43:14 PM »

K9IUQ said:
Quote
I wish you fellows would learn to not Quote the whole post as it makes your post difficult to read. Just quote a little....

Heck, I can barely read the quoted gray text on blue background. So in my posts I'll put important quotes in bold print. And rarely more than two lines.

What a bloated mess some of these posts are. But Flexedge and Flexradio are even worse.
« Last Edit: July 06, 2011, 08:49:21 PM by K0OD » Logged
KE5JPP
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« Reply #81 on: July 07, 2011, 03:44:00 AM »

I have a setup with 8 receivers for an array and they are all connected to a 16 port gigE switch. Then I have a single cable with 8 radios on it.

There are very few hobbyists that are going to be able to afford to spend 8 x $2000 = $16,000 to have the convenience of a one cable connection and to lock all those receivers to a single source.  At least not your typical Ham user.  I know that this is not what your target audience is for this kind of application, but we are on eHam which is meant for Hams, not commercial or government users. 

For sure, you are not going to pass raw IQ data from 8 receivers over the internet.   For the hobbyist, the NetSDR does not add enough features to justify the $500 to $1000 additional cost over the competition.

Gene
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KE5JPP
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« Reply #82 on: July 07, 2011, 03:46:39 AM »

Most people will not attempt to send raw data over the internet. I have tried it with narrow bandwidths and it works fine. The real convenience is being able to put the radio on the intranet where any computer in the house or business can see it.

H'mm... this is what I was saying in my earlier posts and you tried to discredit me for saying it.  Now you are saying it.  Roll Eyes

Gene
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KE5JPP
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« Reply #83 on: July 07, 2011, 03:52:05 AM »

The NetSDR and SDR-IP both use the same ADC and oscillator. The oscillator they use is the same as the Perseus.

So the $1500 NetSDR and the $3000 SDR-IP have the same oscillator as the $1000 Perseus.  Yet, in the link you provided it was claimed that the $3000 SDR-IP had a little better phase noise than the Perseus.  So, what accounts for the difference if both use the same oscillator?  Earlier you stated that it is impossible for there to be a difference.

Gene
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KE5JPP
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« Reply #84 on: July 07, 2011, 05:10:38 AM »

Heck, I can barely read the quoted gray text on blue background. So in my posts I'll put important quotes in bold print. And rarely more than two lines.

You need to get yourself a better monitor.

Gene
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M0HCN
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Posts: 473




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« Reply #85 on: July 07, 2011, 07:15:57 AM »

Getting vaguely back on topic, there is more to phase noise then just the oscillator in use.

Power supply noise, spurs picked up from bad PCB layout, any divider chip (Say for I/Q generation for a mixer) can add noise and of course the ADC will have aperture jitter.....

at below about -150dBc you need to pay massive attention to all of these to get a good result, so phase noise differences between radios using the same clock generator are to be expected. 

This incidentally is why band limiting the RF before the mixer/converter helps (for all it goes against the grain when doing SDR) as it reduces the total noise power for the phase noise to reciprocally mix with. 
 
Ethernet has the potential to be a big win, but for my use case the price would need to come down first, the early stuff is always expensive.

Regards, Dan.
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N4IP
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« Reply #86 on: July 07, 2011, 08:39:08 AM »

Getting vaguely back on topic, there is more to phase noise then just the oscillator in use.

Power supply noise, spurs picked up from bad PCB layout, any divider chip (Say for I/Q generation for a mixer) can add noise and of course the ADC will have aperture jitter.....

at below about -150dBc you need to pay massive attention to all of these to get a good result, so phase noise differences between radios using the same clock generator are to be expected. 

This incidentally is why band limiting the RF before the mixer/converter helps (for all it goes against the grain when doing SDR) as it reduces the total noise power for the phase noise to reciprocally mix with. 
 
Ethernet has the potential to be a big win, but for my use case the price would need to come down first, the early stuff is always expensive.

Regards, Dan.

Dan,

You're right. It is very easy to mess up the phase noise. The clock into the ADC needs to be handled as if it is an analog signal since it will end up mixing with every signal going into the ADC. There are very little drivers available that will not degrade the phase noise. You try not to have to amplify or buffer the clock before it gets to the ADC. We also regulate and use big low pass filters on the DC lines. When we measure the phase noise, we measure the whole chain from RF input to IQ output on the PC side. If there is a problem you will see it.

Pieter
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M0HCN
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Posts: 473




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« Reply #87 on: July 07, 2011, 04:38:22 PM »

One other thing to watch is that phase noise does not tell the whole story, an SSA set to measure PN will in some modes ignore amplitude noise which can be just as big a problem.

See Martein Bakkers work on the AD9910 for some unpleasant plots due to a simple decoupling screwup by AD (Unbypassed on chip bandgap), excellent phase noise performance but the AM noise is painful.

Like all engineering specifications, phase noise data often needs a little qualification and should never be taken as a figure of merit without also considering how it impacts the rest of the radio.

Regards, Dan.
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KI4Z
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Posts: 37




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« Reply #88 on: July 07, 2011, 06:40:04 PM »

SDR is super good for wideband stuff..  aka SSB or wider bandwidths.  It very hard to beat analog filtering (multipe crystal filters with passband tuning and narrow roofing filter at the first IF (~70 Mhz) of an up convert radio. I'd like to see a side by side comparison of the best SDR against a top of the line HF 3 filter (VHF, HF, 455Khz) rig on 7 MHz CW on a quiet night.  For digging out out a 100 mW chirpy CW signal from halfway around the world at the limit of detection, I've never seen any SDR beat top of the line 80's HiPo best in class analog technology. When it get's tough copying them, an old technology DSP analog filter (Love the NIR-12) makes it clear.  IF DSP filters do quite well with specifications, but face it, still sound like crap.  Finding weak signals onDSP rigs with rainfall dispalys and inherent  Bandscope displays is another issue. 

Old fart here with several '80s best in class ICOM HF rigs.  Never heard an SDR that can dig them out like these dinosaurs can..  Prove me wrong.

mark  KI4Z
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KE5JPP
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« Reply #89 on: July 08, 2011, 03:33:08 AM »

Never heard an SDR that can dig them out like these dinosaurs can..  Prove me wrong.
mark  KI4Z

Which SDRs do you have experience with?

Gene
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