Re: [Discuss-gnuradio] AGC and Dynamic Range of ADC
On 09/23/2013 11:07 PM, bob wole wrote: Can somebody please guide me on this ? Bob On Fri, Sep 20, 2013 at 4:44 PM, bob wole address@hidden wrote: I have USRPN210 with WBX and RFX2400. Is there any AGC chip on N210 motherboard or WBX, RFX2400 before ADC to utilize the dynamic range of ADC ? if yes, which one? If not, then won't the varying input signal (for example signal from moving object) to ADC affect the performance of ADC ? Bob The ADC on an N210 has over 80dB of dynamic range. If that isn't enough, then your application can adjust the RF gain to taste. Only a subset of applications actually benefit from the usual hardware AGC schemes, and such schemes are invariably application-specific, so there's no *automatic* gain control. But your application can dynamically make gain adjustments as it goes. Hi Marcus thanks for response, If there is no automatic gain control then how does it is ensured that ADC doesn't saturate ? I mean what if there is a signal whose amplitude is greater that ADC's highest input level ? Won't it saturate the ADC ? Also what if the signal is too weak to span much of the ADC input voltage, then again we are not using all bits effectively. Guide please. Thanks, Bob -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] AGC and Dynamic Range of ADC
On 09/24/2013 10:30 AM, bob wole wrote: On 09/23/2013 11:07 PM, bob wole wrote: Can somebody please guide me on this ? Bob On Fri, Sep 20, 2013 at 4:44 PM, bob wole address@hidden mailto:address@hidden wrote: I have USRPN210 with WBX and RFX2400. Is there any AGC chip on N210 motherboard or WBX, RFX2400 before ADC to utilize the dynamic range of ADC ? if yes, which one? If not, then won't the varying input signal (for example signal from moving object) to ADC affect the performance of ADC ? Bob The ADC on an N210 has over 80dB of dynamic range. If that isn't enough, then your application can adjust the RF gain to taste. Only a subset of applications actually benefit from the usual hardware AGC schemes, and such schemes are invariably application-specific, so there's no *automatic* gain control. But your application can dynamically make gain adjustments as it goes. Hi Marcus thanks for response, If there is no automatic gain control then how does it is ensured that ADC doesn't saturate ? I mean what if there is a signal whose amplitude is greater that ADC's highest input level ? Won't it saturate the ADC ? Also what if the signal is too weak to span much of the ADC input voltage, then again we are not using all bits effectively. Guide please. Thanks, Bob -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org http://www.sbrac.org/ There is nothing to ensure that ADC values are neither too little nor too big. That's up to your application. There's an RF gain control on the WBX, for example, that gives 31.5dB of gain control.If you have very weak signals, then you have to use an external LNA. If your dynamic range requirements exceed the 80dB dynamic range of the ADC, then your application has to account for this, and adjust RF gain accordingly. -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] AGC and Dynamic Range of ADC
Well that is 80 dB of dynamic range inside the Nyquist zone (at best and let's call it N). I can add a bit of increase in dynamic range by downsampling (filter and decimation) and growing the accumulator size by a bit for each decimation by 4. This will increase dynamic range. I don't believe this is happening to a large extent in the N210 unless it is included in you 80 dB number which I believe is you just doing 14 bits of ADC is 80 dB. Bob On Mon, Sep 23, 2013 at 11:54 PM, Marcus D. Leech mle...@ripnet.com wrote: ** On 09/23/2013 11:07 PM, bob wole wrote: Can somebody please guide me on this ? Bob On Fri, Sep 20, 2013 at 4:44 PM, bob wole bnw...@gmail.com wrote: I have USRPN210 with WBX and RFX2400. Is there any AGC chip on N210 motherboard or WBX, RFX2400 before ADC to utilize the dynamic range of ADC ? if yes, which one? If not, then won't the varying input signal (for example signal from moving object) to ADC affect the performance of ADC ? Bob The ADC on an N210 has over 80dB of dynamic range. If that isn't enough, then your application can adjust the RF gain to taste. Only a subset of applications actually benefit from the usual hardware AGC schemes, and such schemes are invariably application-specific, so there's no *automatic* gain control. But your application can dynamically make gain adjustments as it goes. -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortiumhttp://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio -- Bob McGwier Owner and Technical Director, Allied Communication, LLC Professor Virginia Tech Senior Member IEEE, Facebook: N4HYBob, ARS: N4HY Faculty Advisor Virginia Tech Amateur Radio Assn. (K4KDJ) ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] AGC and Dynamic Range of ADC
Can somebody please guide me on this ? Bob On Fri, Sep 20, 2013 at 4:44 PM, bob wole bnw...@gmail.com wrote: I have USRPN210 with WBX and RFX2400. Is there any AGC chip on N210 motherboard or WBX, RFX2400 before ADC to utilize the dynamic range of ADC ? if yes, which one? If not, then won't the varying input signal (for example signal from moving object) to ADC affect the performance of ADC ? Bob ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] AGC and Dynamic Range of ADC
On 09/23/2013 11:07 PM, bob wole wrote: Can somebody please guide me on this ? Bob On Fri, Sep 20, 2013 at 4:44 PM, bob wole bnw...@gmail.com mailto:bnw...@gmail.com wrote: I have USRPN210 with WBX and RFX2400. Is there any AGC chip on N210 motherboard or WBX, RFX2400 before ADC to utilize the dynamic range of ADC ? if yes, which one? If not, then won't the varying input signal (for example signal from moving object) to ADC affect the performance of ADC ? Bob The ADC on an N210 has over 80dB of dynamic range. If that isn't enough, then your application can adjust the RF gain to taste. Only a subset of applications actually benefit from the usual hardware AGC schemes, and such schemes are invariably application-specific, so there's no *automatic* gain control. But your application can dynamically make gain adjustments as it goes. -- Marcus Leech Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] AGC and Dynamic Range of ADC
I have USRPN210 with WBX and RFX2400. Is there any AGC chip on N210 motherboard or WBX, RFX2400 before ADC to utilize the dynamic range of ADC ? if yes, which one? If not, then won't the varying input signal (for example signal from moving object) to ADC affect the performance of ADC ? Bob ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
