14 Jan
2014
14 Jan
'14
3:23 p.m.
Hi,
Is there any information or hint on the settling time after new frequency
set to dongle?
Or is there any method to read information from dongle to see if all things
get stable?
Can I immediately read samples after new frequency is set by
rtlsdr_set_center_freq?
If so, will the samples quality be degraded?
Thanks!
BR
Jiao Xianjun
14 Jan
14 Jan
4:11 p.m.
Yes, you can read traffic immediately after setting new frequency. No
settling needed ;-)
Just make sure your read buffer is at least 512 B or libusb_bulk_transfer
will fail :-(
BR,
Nikos
On Tue, Jan 14, 2014 at 4:23 PM, Jiao Xianjun <putaoshu(a)gmail.com> wrote:
Hi,
Is there any information or hint on the settling time after new frequency
set to dongle?
Or is there any method to read information from dongle to see if all
things get stable?
Can I immediately read samples after new frequency is set by rtlsdr_set_center_freq?
If so, will the samples quality be degraded?
Thanks!
BR
Jiao Xianjun
4:20 p.m.
Settling time should be wery small (up to few tenths of ms or even
faster), internal
buffering in dongle is also small.
You should drop few thousand samles to be sure all is fine.
This results are from observation, not from measurement, can someone
provide hard data?
Dne 14.1.2014 15:23, Jiao Xianjun napsal(a):
Hi,
Is there any information or hint on the settling time after new frequency
set to dongle?
Or is there any method to read information from dongle to see if all things
get stable?
Can I immediately read samples after new frequency is set by
rtlsdr_set_center_freq?
If so, will the samples quality be degraded?
Thanks!
BR
Jiao Xianjun
4:50 p.m.
New subject: What's the settling time after new frequency set to dongle?
Hi,
On 2014-01-14 15:23, Jiao Xianjun wrote:
Is there any information or hint on the settling time
after new
frequency set to dongle?
That depends a bit on the tuner and the sample FIFO of the RTL2832,
but you need to drop a few buffers, as the PLL of the tuner takes
some time to lock and stabilize.
Can I immediately read samples after new frequency is
set by
rtlsdr_set_center_freq? If so, will the samples quality be degraded?
Kyle Keen did some experiments for his scanning application
(rtl_power), and he settled for waiting a few milliseconds and
flushing the buffer to get optimal results. See here:
http://cgit.osmocom.org/rtl-sdr/tree/src/rtl_power.c#n626
Regards,
Steve
5:47 p.m.
On Tue, Jan 14, 2014 at 5:50 PM, <steve(a)steve-m.de> wrote:
Hi,
On 2014-01-14 15:23, Jiao Xianjun wrote:
empty due
to interfernce, noise, etc.
Is there any information or hint on the settling
time after new
frequency set to dongle?
That depends a bit on the tuner and the sample FIFO of the RTL2832,
but you need to drop a few buffers, as the PLL of the tuner takes
some time to lock and stabilize.
Sample FiFO should be full at all times in a DVB-T. I have never seen it
Can I immediately read samples after new frequency is set by
scanner I use a read immediately after the frequency
set without any problems. Of course I cannot vouch for correct frequency,
but I have noticed that the frequency doesn't drift
appreciably when resetting frequency and locking to a band.
BR,
Nikos
rtlsdr_set_center_freq? If so, will the samples
quality be degraded?
Kyle Keen did some experiments for his scanning application
(rtl_power), and he settled for waiting a few milliseconds and
flushing the buffer to get optimal results. See here:
http://cgit.osmocom.org/rtl-sdr/tree/src/rtl_power.c#n626
Regards,
Steve
That's a little too long, making large spectrum tuners inoperable. In my
8:26 p.m.
We forgot the most important parameter. The frequency "jump". If the
frequency change is large, i.e. from 10 Khz to 1 Ghz, then of course it
will take longer for the tuner to equilibrate. In my scanner, when I
approach a target I take 10 baby steps of 2 Khz each to zero in. Drift is
negligible. I tried using the 5000 us in my scanner, and the results were
the same as without it, except for the delay of an additional 50 s. I
promptly removed it.
The way I see it, tuner needs some time to settle in a new frequency, but
there is no fixed delay. It is situation specific and depends highly on the
amount of frequency change.
HTH,
Nikos
On Tue, Jan 14, 2014 at 6:47 PM, Nikos Balkanas
<nikos.balkanas(a)eyeonix.com>wrote;wrote:
On Tue, Jan 14, 2014 at 5:50 PM, <steve(a)steve-m.de> wrote:
Hi,
On 2014-01-14 15:23, Jiao Xianjun wrote:
empty due
to interfernce, noise, etc.
Is there any information or hint on the settling
time after new
frequency set to dongle?
That depends a bit on the tuner and the sample FIFO of the RTL2832,
but you need to drop a few buffers, as the PLL of the tuner takes
some time to lock and stabilize.
Sample FiFO should be full at all times in a DVB-T. I have never seen it
Can I immediately read samples after new frequency is set by
scanner I use a read immediately after the frequency
set without any problems. Of course I cannot vouch for correct frequency,
but I have noticed that the frequency doesn't drift
appreciably when resetting frequency and locking to a band.
BR,
Nikos
rtlsdr_set_center_freq? If so, will the samples
quality be degraded?
Kyle Keen did some experiments for his scanning application
(rtl_power), and he settled for waiting a few milliseconds and
flushing the buffer to get optimal results. See here:
http://cgit.osmocom.org/rtl-sdr/tree/src/rtl_power.c#n626
Regards,
Steve
That's a little too long, making large spectrum tuners inoperable. In my
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5 comments
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participants (4)
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Jiří Pinkava -
Nikos Balkanas -
steve＠steve-m.de