decoding

[solarflow99]

I was just wondering why more scanners don't have digital codecs built into them? When you think about it, receiving analog is not very sophisticated, especially now that so much RF is going digital. All you pickup these days is noise.

 

[wb0wao]

The software required to decode a specific method of digital encoding is proprietary, that is, it is not an open standard that can be used by just anyone. You have to have a license by the owner of the format and, IIRC, it costs about $100 for the P25 license. Assuming for a moment that this cost would be comperable for other modes, if you had a scanner capable of monitoring P25, MotoTRBO, NXDN and OpenSky - that would add $500 to the price of the scanner before you even built it! How many people would spend upwards of $900 to $1K for this capability?

Give that, some digital formats will NEVER be offered in a scanner because there has been a decision by the owner of that format to not release it - OpenSky for example. They use this as a marketing point to sell the system - "It is impossible to monitor traffic on our system with a scanner!" You cannot reverse engineer a format and then offer it without getting a major lawsuit filed against you, much less getting the scanner type accepted. It isn't a technical issue but a legal issue that has kept scanners capable from monitoring some formats.

That being said, EVENTUALLY you will most likely see MotoTRBO and NXDN capable scanners within then next 5 years or so as the number of agencies moving to those formats increases and simple economics tells us that if there is a demand for a product, someone will provide that product. AFAIK, ^^ and Icom/Kenwood would probably license their use in scanners.

Again, there is no technical reason that they could not develop a analog/digital scanner with P25, MotoTRBO, NXDN, OpenSky, Pro-Voice etc. capability - but the reasons are legal and economic.

 

[jackj]

I don't understand your post WB0WAO. Do you mean that there aren't any scanners that can decode digital communications? My BCD996T decodes P25 standard, Motorola Type II P25,, LTR, EDACS and Motorola Type I (which is a trunked analog system, I think). I could be wrong but I believe that the P25 standard is public domain, I don't know about the others.

 

[rfradioconsult]

No P25 is not an open standard, it is owned by DVSI; they have chosen to license it to scanner manufacturers, that is why a P25 capable scanner costs $500 and up, included in that price is a license fee.

 

[jackj]

I thought that I had read somewhere that P25 was freely available to developers and manufacturers. The standard had been developed by a consortium of manufacturers (or maybe it was a semi-governmental body). You may very well be right but what about the other digital schemes? If Uniden payed a licensing fee for them too then the cost of the licenses was probably more than the cost of the scanner.

In any case solarflow99, there are a lot of digital capable scanners on the market today. Some areas of the country haven't gone digital and probably won't for at least a decade so there is still a market for the less expensive, analog only, scanners.

 

[jackj]

I did a quick search and came up with P25.com. I quote:

"The Project 25 standard organization is comprised of the Association of Public Safety Communications Officials (APCO), the National Association of State Telecommunications Directors (NASTD) and the U.S. Federal Government. The Telecommunications Industry Association (TIA) offers manufacturers representation in the standard's creation and modification."

This group developed the P25 standard and it appears that they own the rights to it. I didn't dig too deep but it looks like it IS an open standard. The company you mentioned, DVSI, developed the vocoder used in P25 and I don't know how the rights to the vocoder are handled but the vocoder is just one small part of the standard.

 

[wb0wao]

I don't understand your post WB0WAO. Do you mean that there aren't any scanners that can decode digital communications? My BCD996T decodes P25 standard, Motorola Type II P25,, LTR, EDACS and Motorola Type I (which is a trunked analog system, I think). I could be wrong but I believe that the P25 standard is public domain, I don't know about the others.

LTR, EDACS, and Motorola Type 1 and 2 are not digital formats - they are trunking schemes. Now digital modes can be on these systems, but not always. AmerenUE is EDACS but in analog, Paducah Public Safety is Motorola Type 2 and also analog, and all of the LTR systems in Cape are analog.

Terminology is key here - P25 is a digital mode but EDACS is a system.

To the second point... yes the system architecture for P25 is "open", that is to say that how the analog signal is converted to digital as well as other sundry functions are published for all to see. DVSI developed a chip that does all of that automagically and sells it to the OEM scanner companies. The licensing fee is for the use of their chip and embedded software.