Analog and digital freqs? Dazed 'n' confused . . .

[Sherrikat]

Hey, all -

I just bought a Whistler WS1025 Analog Desktop Scanner because my old (and I mean OLD!) RadioShack Pro 2010 finally gave up the ghost.

But I'm really confused about a couple of things:

First, are frequencies themselves analog or digital? I thought the difference was just how the sound is presented, but now I'm seeing that some police systems are on digital. (I think that's what I'm seeing.) So, I retired to Bloomington, Indiana from Chicago a few months ago and the police/fire freqs for Btown look like the ones for Chicago, ie, 3 numbers starting with a 1 or 4, then decimals, then 3 more numbers. Like: 460.225. Does that mean they're analog since I got them on my old 2010?

Second, I have never really understood what the "input" number next to the frequency means. Example below. What's the diff between Frequency and Input?

Frequency Input Callsign Description
154.190000 * 156.01500 * WPMD622* Fireground 5 - Bloomington Twp *

 

[wyShack]

Frequencies are neither analog or digital. What is either digital or analog is the modulation (how the information is 'placed' on the carrier (or channel or frequency). To further complicate the situation, a voice can be digitized and then the (digital) information placed on the carrier by an analog method. For the most part simple AM or FM is considered analog while most would consider everything else 'digital'.

Another thing you are bound to run into (or already have ) is trunking-See the Wiki.

To answer you other question, many radio systems use repeaters to extend range. A repeater 'listens' on one frequency (the input) and re-transmits what it hears on the 'output' (or repeater frequency). For the most part, listening on the output is all you need to do. If you hear anything on the 'input' it likely meas the unit is close to you ( or withing line of sight) while units heard only on the repeater could be anywhere within the repeater's coverage area. As repeater are often placed on high hills or tall towers, they tend to cover large areas compared to a handheld or mobile unit.

Got a bit long winded-hope the above helps you.

 

[Sherrikat]

wyShack, thank you!! This definitely helps. OK, off to look up "trunking" . . .

 

[Sherrikat]

Hoo boy, wyShack. I think I made a wrong decision. So, according to Wiki . . .

"Scanners are made to decode P25 digital modulation, but that capability comes at a premium price. There are other digital modes that you may run across during your research, for example: VSELP (not monitorable) or OpenSky (not monitorable). The thing to remember is today the only digital mode used that is monitorable by today's scanners is APCO-25 (P25 CAI). (Don't confuse the P25 Common Air Interface, which is just the audio encoding method, with Project 25 which is the entire trunking system, with a 9600bps control channel.)"

And, here is Monroe County, Indiana's info on RadioReference frequencies:

Bloomington Police

Indiana Project Hoosier SAFE-T (P-25)
Project 25 Phase I Used by all Bloomington Public Safety

Frequency License Type Tone Alpha Tag Description Mode Tag
460.32500 KNCL547 RM 88.5 PL Blmng PD 1 Police Dispatch F1 FMN Deprecated
453.05000 KNCL547 RM Blmng PD 2 Police Operations F2 FMN Deprecated
460.32500 KNCL547 RM Blmng PD 3 Police Talkaround UHF FMN Deprecated

So, the Whistler WS1025 is an analog scanner and it looks like I need a digital scanner . . . right? Maybe I'm not reading this right - still a bit confused.

 

[ofd8001]

Good explanation above.

Bringing it a little closer to home. Your area appears to participate in the Indiana state radio system, which uses a digital format. (They used to have their own system which used an analog format).

See Indiana Project Hoosier SAFE-T (P-25) Trunking System, Statewide, Multi-State - Scanner Frequencies and scroll down to Monore county talkgroups. I believe the Hindustan and Bloomington towers are the applicable sites, but would defer to a local user's knowledge to confirm.

 

[Sherrikat]

ofd8001, I think you are correct. I think I figured that out and reposted, but because I'm new, it has to go through the mods, first. Thanks to both of you! Will send my Whistler analog back for a digital!