I would expect the noise floor to change when varying the
filter bandwidth. The thermal noise floor should be equal to:
P = kTB
where B is equal to bandwidth (k is Boltzmann's constant
and T is temperature) . For room temperature, the
thermal noise floor in dBm can be simplified to:
P(dBm) = -174 + 10log (B)
So for a 6 MHz bandwidth, the noise floor is at -106 dBm, but
at 10 kHz, it's at -134 dBm. Since we're interested in signal to
noise ratio, the filter bandwidth makes a big difference.
Your actual noise floor will be degraded by the noise figure of the
dongle and any man made noise at your location.
BTW, the pics you posted to the group photo folder are too small
to be able to see much.
Yes the bandwidth is continuously adjustable and is displayed on the left side, but the screen displays up to two megaHertz at a time and signal levels don't change when narrowing the bandwidth or narrowing the spectrum displayed. The only thing that will change the signal level is opening configuration and changing the RF Gain. You can change the bandspread to display only about 100 hz and the level of a signal remains the same as when it displayed 2 mHz. You can narrow the filter to 600 Hz or widen it to 250000 and no difference.
I thought I was ordering a neat toy but it has turned out to be no toy, but a capable SDR and spectrum monitor 24-1700mHz. I was just reading someone's post about SDRs written in 2010 and the guy was saying that it would cost in the thousands to buy an SDR that really worked at VHF and UHF frequencies. How time flies! I listened to the NA QSO Party last weekend on 10 meters and after getting used to the waterfall and figuring out how to use it to tune SSB signals, it was very competitive with my IC-706mkIIg.
I see that they have similar dongles for ATSC TV that run about $30-40, but no SDR capability yet there.
Mark5R wrote:I'm up and running. Excellent
Users browsing this forum: No registered users and 1 guest