Re: [Flexradio] FW: Impulse Wave file
richard allen wrote: In our military system tests we acquire 10-20 impulses and sum them in the frequency domain. If the ripple is actually in the system then it will stay in. This was what the generals all wanted. In our seismic stuff, where the geophysicists seem to think it is needed to find oil, we require the 1 dB flatness in the frequency domain plateau of a single impulse. In the VLBI world, we continuously inject weak pulses at a 1 MHz rate (1 usec between pulses) which have rise times in the 10s of psec range. These pulses, injected into the radio astronomy receiver front ends, manifest themselves as a frequency rail every 1 MHz. To achieve a very wide (upwards of 1 GHz) flat passband, these phase cal signals are processed to determine the phase offset needed to bring them all into line. The pulse generator that Gerald built into the the SDR-1000 is my design, derived from the same concept. In the VLBI world, we adjust the pulse amplitude so that it only increases the wideband system temperature by only 1-2%, but the pulses are seen with good SNR as frequency rails in FFT analyzers running a few Hz bandwidth. 73, Tom
Re: [Flexradio] FW: Impulse Wave file
That is what I did. I turned on the wave file record on the main menu and did a bunch of automatic pulse generations. Everyone jump on Eric with me. TURN THIS CONTROL ON THERE IS LOTS OF INTEREST. ;-) Bob richard allen wrote: Another thing about the impulse generator in my system at work. The impulse starts 1/3 of the way between sample intervals, and lasts 1/3 sample interval. This guarantees that all of the energy falls between two sampling points. The sample rate is typically 500 or 1000 Hz. However , since the impulse is routed thru the front end low -cuts and preamps which have a certain amount of delay, it is unclear to me what the importance of the centering is. It does of course produce results that are reproducable from one day to the next and may be the result of a bit of specsmanship :) Are you planning on having this generator complete to the point of producing a short .wav file for outside analysis? Richard Robert McGwier [EMAIL PROTECTED] wrote: (11/23/2005 22:31) -- Laziness is the number one inspiration for ingenuity. Guilty as charged!
Re: [Flexradio] FW: Impulse Wave file
In our military system tests we acquire 10-20 impulses and sum them in the frequency domain. If the ripple is actually in the system then it will stay in. This was what the generals all wanted. In our seismic stuff, where the geophysicists seem to think it is needed to find oil, we require the 1 dB flatness in the frequency domain plateau of a single impulse. Another possible problem is that the data before and after the impulse must be un-modified by another impulse coming along for at least the time to get thru the last fir filter stage in the sigma- delta converters. This takes 29 samples in our seismic converters. At that point the response should have dropped to zero, of course, but any analog stuff may still be banging about. I usually play it safe and isolate a single impulse in 1024 samples. I did not measured the time between the individual pulses in your data. Impulse respone image is at http://rcallen.com/iqimp.png in case anyone else wants to see it. Richard W5SXD Robert McGwier [EMAIL PROTECTED] wrote: (11/23/2005 18:21) There is enough there to tell me that we should have done the block equalizer a long time ago. I did not know about the ripple and the delay elements they imply. Bob richard allen wrote: One more time. -Original Message- From: richard allen [mailto:[EMAIL PROTECTED] Sent: Wednesday, November 23, 2005 7:36 AM To: 'Robert McGwier' Cc: [EMAIL PROTECTED] Subject: RE: [Flexradio] Impulse Wave file Looks pretty flat. Seismic stuff is spec'ed at 1 db flatness. Analysis of a single of your impulses. I guess you'll need to sum a bunch. Richard -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Robert McGwier Sent: Tuesday, November 22, 2005 9:23 PM To: [EMAIL PROTECTED] Biz Subject: [Flexradio] Impulse Wave file We have an impulse generator on the RFE. And we have (currently hidden) code to generate a train of pulses. I generated several ten long pulse trains with the RFE impulse generator and made a wave file. The large pop at the end of the file is me disengaging the impulse relay. ftp.flex-radio-friend.net u: Friends p: Flex4U cd upload/N4HY get IQ_impulses.wav Bob -- Laziness is the number one inspiration for ingenuity. Guilty as charged!
Re: [Flexradio] FW: Impulse Wave file
There should have been 2048 samples between. If there is not, I made a mistake and will do the file again. We definitely need the equalizer. Bob richard allen wrote: In our military system tests we acquire 10-20 impulses and sum them in the frequency domain. If the ripple is actually in the system then it will stay in. This was what the generals all wanted. In our seismic stuff, where the geophysicists seem to think it is needed to find oil, we require the 1 dB flatness in the frequency domain plateau of a single impulse. Another possible problem is that the data before and after the impulse must be un-modified by another impulse coming along for at least the time to get thru the last fir filter stage in the sigma- delta converters. This takes 29 samples in our seismic converters. At that point the response should have dropped to zero, of course, but any analog stuff may still be banging about. I usually play it safe and isolate a single impulse in 1024 samples. I did not measured the time between the individual pulses in your data. Impulse respone image is at http://rcallen.com/iqimp.png in case anyone else wants to see it. Richard W5SXD Robert McGwier [EMAIL PROTECTED] wrote: (11/23/2005 18:21) There is enough there to tell me that we should have done the block equalizer a long time ago. I did not know about the ripple and the delay elements they imply. Bob richard allen wrote: One more time. -Original Message- From: richard allen [mailto:[EMAIL PROTECTED] Sent: Wednesday, November 23, 2005 7:36 AM To: 'Robert McGwier' Cc: [EMAIL PROTECTED] Subject: RE: [Flexradio] Impulse Wave file Looks pretty flat. Seismic stuff is spec'ed at 1 db flatness. Analysis of a single of your impulses. I guess you'll need to sum a bunch. Richard -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Robert McGwier Sent: Tuesday, November 22, 2005 9:23 PM To: [EMAIL PROTECTED] Biz Subject: [Flexradio] Impulse Wave file We have an impulse generator on the RFE. And we have (currently hidden) code to generate a train of pulses. I generated several ten long pulse trains with the RFE impulse generator and made a wave file. The large pop at the end of the file is me disengaging the impulse relay. ftp.flex-radio-friend.net u: Friends p: Flex4U cd upload/N4HY get IQ_impulses.wav Bob -- Laziness is the number one inspiration for ingenuity. Guilty as charged! -- Laziness is the number one inspiration for ingenuity. Guilty as charged!
Re: [Flexradio] FW: Impulse Wave file
Looks like there is about 50 ms between them. see http://rcallen.com/iqimps.png The sine wave at the end is at 48000/2048 Hz period 42.666 ms Richard Robert McGwier [EMAIL PROTECTED] wrote: (11/23/2005 20:29) There should have been 2048 samples between. If there is not, I made a mistake and will do the file again. We definitely need the equalizer. Bob richard allen wrote: In our military system tests we acquire 10-20 impulses and sum them in the frequency domain. If the ripple is actually in the system then it will stay in. This was what the generals all wanted. In our seismic stuff, where the geophysicists seem to think it is needed to find oil, we require the 1 dB flatness in the frequency domain plateau of a single impulse. Another possible problem is that the data before and after the impulse must be un-modified by another impulse coming along for at least the time to get thru the last fir filter stage in the sigma- delta converters. This takes 29 samples in our seismic converters. At that point the response should have dropped to zero, of course, but any analog stuff may still be banging about. I usually play it safe and isolate a single impulse in 1024 samples. I did not measured the time between the individual pulses in your data. Impulse respone image is at http://rcallen.com/iqimp.png in case anyone else wants to see it. Richard W5SXD Robert McGwier [EMAIL PROTECTED] wrote: (11/23/2005 18:21) There is enough there to tell me that we should have done the block equalizer a long time ago. I did not know about the ripple and the delay elements they imply. Bob richard allen wrote: One more time. -Original Message- From: richard allen [mailto:[EMAIL PROTECTED] Sent: Wednesday, November 23, 2005 7:36 AM To: 'Robert McGwier' Cc: [EMAIL PROTECTED] Subject: RE: [Flexradio] Impulse Wave file Looks pretty flat. Seismic stuff is spec'ed at 1 db flatness. Analysis of a single of your impulses. I guess you'll need to sum a bunch. Richard -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Robert McGwier Sent: Tuesday, November 22, 2005 9:23 PM To: [EMAIL PROTECTED] Biz Subject: [Flexradio] Impulse Wave file We have an impulse generator on the RFE. And we have (currently hidden) code to generate a train of pulses. I generated several ten long pulse trains with the RFE impulse generator and made a wave file. The large pop at the end of the file is me disengaging the impulse relay. ftp.flex-radio-friend.net u: Friends p: Flex4U cd upload/N4HY get IQ_impulses.wav Bob -- Laziness is the number one inspiration for ingenuity. Guilty as charged! -- Laziness is the number one inspiration for ingenuity. Guilty as charged!
Re: [Flexradio] FW: Impulse Wave file
Yep:
private void btnImpulse_Click(object sender, System.EventArgs e)
{
for(int i=0; i(int)udImpulseNum.Value; i++)
{
console.hw.Impulse();
Thread.Sleep(45);
}
}
Nothing special or fancy. Fire, wait, fire, wait.
richard allen wrote:
Looks like there is about 50 ms between them.
see http://rcallen.com/iqimps.png
The sine wave at the end is at 48000/2048 Hz period 42.666 ms
Richard
--
Laziness is the number one inspiration for ingenuity. Guilty as charged!
Re: [Flexradio] FW: Impulse Wave file
Another thing about the impulse generator in my system at work. The
impulse starts 1/3 of the way between sample intervals, and lasts 1/3
sample interval. This guarantees that all of the energy falls
between two sampling points. The sample rate is typically 500 or
1000 Hz. However , since the impulse is routed thru the front end low
-cuts and preamps which have a certain amount of delay, it is unclear
to me what the importance of the centering is. It does of course
produce results that are reproducable from one day to the next and
may be the result of a bit of specsmanship :)
Are you planning on having this generator complete to the point of
producing a short .wav file for outside analysis?
Richard
Robert McGwier [EMAIL PROTECTED] wrote:
(11/23/2005 22:31)
Yep:
private void btnImpulse_Click(object sender, System.EventArgs e)
{
for(int i=0; i(int)udImpulseNum.Value; i++)
{
console.hw.Impulse();
Thread.Sleep(45);
}
}
Nothing special or fancy. Fire, wait, fire, wait.
richard allen wrote:
Looks like there is about 50 ms between them.
see http://rcallen.com/iqimps.png
The sine wave at the end is at 48000/2048 Hz period 42.666 ms
Richard
--
Laziness is the number one inspiration for ingenuity. Guilty as charged!
