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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Wireless and Communications => Topic started by: Andrew Broughton on April 10, 2018, 03:56:55 pm

Title: WWB Scan differences between products
Post by: Andrew Broughton on April 10, 2018, 03:56:55 pm
I have some PSM1000 and UR4D and was using both to scan as the UR4D is in a higher range than the PSM1000.
However, the scan that the UR4D is producing in WWB has a "floor" that's about 20db higher than the PSM1000, and in the overlap area, the scan is not the same. Now the difference in the scan could have to do with the location of the 2 devices being in a different location when I scanned that day, but this "floor" of 20db seems very strange. Both receivers in the UR4D produce scans that look the same, with that same raised "floor" and higher/different readings than the PSM.

Any idea what's going on here? (The PSM is the lower trace)
Title: Re: WWB Scan differences between products
Post by: Jordan Wolf on April 10, 2018, 04:13:06 pm
I have some PSM1000 and UR4D and was using both to scan as the UR4D is in a higher range than the PSM1000.
However, the scan that the UR4D is producing in WWB has a "floor" that's about 20db higher than the PSM1000, and in the overlap area, the scan is not the same. Now the difference in the scan could have to do with the location of the 2 devices being in a different location when I scanned that day, but this "floor" of 20db seems very strange. Both receivers in the UR4D produce scans that look the same, with that same raised "floor" and higher/different readings than the PSM.

Any idea what's going on here? (The PSM is the lower trace)
Yeah, anytime I scan with UHF-Rs, the noise floor baselines at -100.

ULX-D, QLX-D show up as your PSM1000 does - lower and with better resolution, IMO.
Title: Re: WWB Scan differences between products
Post by: Andrew Broughton on April 10, 2018, 04:48:17 pm
Yeah, anytime I scan with UHF-Rs, the noise floor baselines at -100.

ULX-D, QLX-D show up as your PSM1000 does - lower and with better resolution, IMO.
Ok, thanks!
Title: Re: WWB Scan differences between products
Post by: Russell Ault on April 11, 2018, 06:10:01 am
I have some PSM1000 and UR4D and was using both to scan as the UR4D is in a higher range than the PSM1000.
However, the scan that the UR4D is producing in WWB has a "floor" that's about 20db higher than the PSM1000, and in the overlap area, the scan is not the same. Now the difference in the scan could have to do with the location of the 2 devices being in a different location when I scanned that day, but this "floor" of 20db seems very strange. Both receivers in the UR4D produce scans that look the same, with that same raised "floor" and higher/different readings than the PSM.

Any idea what's going on here? (The PSM is the lower trace)

Not speaking to the noise floor, but ~30dB extra signal being received by your UR4Ds seems like a lot of extra signal to me. What antennas/distro are you using with the UR4Ds, and was the PSM near one of your RX antennas when you did its scan?

-Russ
Title: Re: WWB Scan differences between products
Post by: Jason Glass on April 11, 2018, 05:43:13 pm
Edit: I totally misunderstood your post.
Title: Re: WWB Scan differences between products
Post by: Andrew Broughton on April 11, 2018, 06:07:45 pm
Here's a scan with the 2 receivers in the same place. The PSM1000 has it's normal wire antennas, the UR4D has the 1'-ish whips that they come with, no distro for the UR4D as I only have the 1 unit.

The scans match in some places but in others the UR4D has a higher reading, like the 1st bump around 521Mhz... Any thoughts as to what's going on there?
Title: Re: WWB Scan differences between products
Post by: Pete Erskine on April 11, 2018, 06:43:06 pm
Here's a scan with the 2 receivers in the same place. The PSM1000 has it's normal wire antennas, the UR4D has the 1'-ish whips that they come with, no distro for the UR4D as I only have the 1 unit.

The scans match in some places but in others the UR4D has a higher reading, like the 1st bump around 521Mhz... Any thoughts as to what's going on there?

The PSM1000 has less sensitivity than the mic RX.  Artificially the noise floor is a straight line and not a real measurement.  That they essentially match in the peaks shows that they are doing the same scan.

Title: Re: WWB Scan differences between products
Post by: Andrew Broughton on April 11, 2018, 09:07:27 pm
Thanks, Pete.

That they essentially match in the peaks shows that they are doing the same scan.
Except where they don't. What do you make of that?
Title: Re: WWB Scan differences between products
Post by: Pete Erskine on April 12, 2018, 10:15:18 am
Thanks, Pete.
Except where they don't. What do you make of that?

no two scanners from different manu will ever totally match  all that is important is seeing where the dtv is, not the actual detail.  zoom in to 1 mhz wide to see a freqs detail.
Title: Re: WWB Scan differences between products
Post by: Jordan Wolf on April 12, 2018, 10:39:35 am
no two scanners from different manu will ever totally match  all that is important is seeing where the dtv is, not the actual detail.  zoom in to 1 mhz wide to see a freqs detail.
Pete,

Both devices are from Shure; one is a UHF-R receiver and one is a PSM1000 receiver.

I guess their RF stages are tuned for somewhat different end uses?

The variation between scans shows +/-10 around the start freq. of TV23.

Iím curious as well - is this amount of difference typical?
Title: Re: WWB Scan differences between products
Post by: Andrew Broughton on April 12, 2018, 03:05:07 pm
no two scanners from different manu will ever totally match  all that is important is seeing where the dtv is, not the actual detail.  zoom in to 1 mhz wide to see a freqs detail.
Understood. Just FYI, the products are both Shure.