PSR-800 Scanning Wireless Microphone & Intercom Frequencies

[wmetech1]

Hello all.

I have a part time job doing general sound/lighting/maintenance work in a theater. One day over the weekend, out of boredom, I decided to program the wireless mic and intercom frequencies into my PSR-800 via the EZ Scan software. When entering in any of the 12+ frequencies I have, I recieve the error "The frequency you entered is invalid for the currently selected country band plan." My selected band plan is USA.

For example, here are the first 3 frequencies:
655.500 Mhz
663.000 Mhz
665.250 Mhz

 

[KB7MIB]

Wirelessly posted (Mozilla/5.0 (X11; Linux i686; U; en-US) Gecko/20081217 Vision-Browser/8.1 301x200 LG VN530)

Few general coverage receivers or scanners cover the range of 512-764 MHz. Without one you're out of luck.

 

[dgmaley]

Gaps

Most scanners, including this one, will have gaps in their frequency coverage. This is due to physics and how the scanner is designed. Eliminating these gaps would increase cost with little benefit. A scanner may actually work in these areas but the designer elected to block them most likely because of the excessive noise or poor performance it would have.
The PSR800 will not receive these areas:
54 to 108Mhz
174-216Mhz
512-764Mhz
782-791Mhz
797-806Mhz
960-1240Mhz
above 1300Mhz

I have had radios that advertise no gaps, but will have areas where the receiver is nearly deaf.

Dave...

 

[Ed_Seedhouse]

Most scanners, including this one, will have gaps in their frequency coverage. This is due to physics and how the scanner is designed.

And just what would the "physics" part be?

General purpose receivers sold in the USA and Canada must, by law, have certain bands disabled. There is no physical reason for this as a receiver with a bandwidth that extends to 3 gig will have no difficulty at all with the lower frequencies unless they are blocked.

They are blocked by filters, which are added electronic circuits. IF you have the proper credentials you can usually purchase these receivers unblocked.

And if you have the required skills and a disregard for the law you can generally disable the filters and receive the bands you want. I have neither the skills nor the desire.

Nothing in physics prevents a wide band receiver from receiving any band below it's HF cutoff except the included filters which are requirements of the law, not of physics.

 

[dgmaley]

Blocked Frequencies

Ed;

You are partially right.
There is still an old scanner law the prevents scanners from being able to receive cell phone calls around 850Mhz. This law is now a waste since 1. Most providers use a different frequency range and 2. It is now all digital and no scanner can decode it.
The federal government got real sticky and also stipulated that scanners couldn't be modified to receive this band either. It used to be able to monitor analog phone calls by listening on the scanner's image frequency. Each scanner model had a different image to calculate. An easy way to prevent this was to calculate the image frequencies and block them in software.
The PSR800 has a very high first IF frequency of 380.1Mhz. This would make an image frequency so far out as to be useless.
Still, the only Federal law is for Cell phones. I can't find any others to be blocked.

Dave..

 

[jackj]

Also the old cell phone frequencies are disabled in the programing, not by filters.

 

[Ed_Seedhouse]

Also the old cell phone frequencies are disabled in the programing, not by filters.

Well a technically filter implemented in the digital domain by programming is still a filter. But thanks for the correction.

 

[Halfpint]

Just for `hallibut' I went and dug out a couple of my old, pre ECPA, AOR scanners, programmed in those freqs, and a few others in the same range, and went over to friend's who just happens to like `playing with' commercial wireless mics. (He happens to do a fair bit of work with those and other `stage related hardware'.) I was able to reliably receive pretty much all we tried out to almost 50yds away, across open space with only one wood framed outside wall between the transmitters and the scanners using one or two of my `oddball', collected over the years off collecting various antennas, antennas. (The reason I say `almost' 50yds is that I forgot to bring along my 300' tape measure and we were using one of those `laser rangefinders that hunters like to buy and I've always been somewhat skeptical as to their accuracy.) I suspect that *if* I actually had an antenna that was cut specifically made for that range I could have gotten even better reception with either scanner.

Unfortunately, I haven't seen either models for sale for quite sometime and even as old as they may be they may demand a fairly premium price if they are in decent condition.

 

[redburgundy]

Scanner receivers are designed with IFs that limit the frequencies that can be received. It would be possible to build a receiver with a wideband tuner that is not limited by IFs, but of course that won't happen.
But it will happen to cable TV set top boxes:
www.broadcom.com/collateral/wp/3128-WP100.pdf
Advanced Direct Conversion Cable Tuner - BCM3421 | Broadcom

 

[jackj]

No

Well a technically filter implemented in the digital domain by programming is still a filter. But thanks for the correction.

Ed, a filter reduces the signal. Scanner just won't accept programing for cell phones. That's not a filter.