Range Test: P25 Digital vs. Analog

Eric, K6ERC, and I conducted a range test on Friday, using a Motorola Astro handie-talkie to compare the transmission range between digital P25 and conventional analog. Eric was at a base station where the antenna is on a short tower and I drove into the field with the HT.

The testing was non-scientific and was on a 147 MHz. amateur channel. Five locations were tested, the most distant 11 miles from the base. A Uniden P25-capable scanner was used as the receiver.

Results

Received signal levels were, not unexpectedly, the same for both P25 and analog signals transmitted from the same location.

The difference was in the quality of the recovered signal. Except for the very closest test location, the P25 signal was easier to listen to and understand than the analog signal. For example, at the last location where we had a useful signal, the P25 rated 4.5 (on a five-point scale) for intelligibility, while analog rated a 2.5.

At the point where P25 could no longer be decoded, the analog signal could still be detected, but was not intelligible. This squares with the concept that P25 works fine until it stops working — the digital error rate becomes too high — while an analog signal fades into unintelligibility.

Conclusion

Based on this small, unscientific test, P25 considerably extends the range of intelligibility of a simplex handie-talkie signal on VHF frequencies. The receiver was located at a place known to suffer from significant amounts of VHF noise, which may have impacted our findings. Nevertheless, given a choice, I would use P25 for simplex VHF communications whenever possible.

What's the address?

I was sitting at a water station on a March of Dimes walk Saturday. Started thinking about what I would do "if."

First, in this really informal situation, I'd call 911 before talking to net control. I started thinking about how I'd describe the location if I made the call.

"Magnolia Street on the CSU campus, by the water tower" would work. But, the actual address would work better.

Dispatch systems much prefer street addresses when figuring out who to send.

Even out in the sticks, it is often possible to conjure up a street address. Some GPS apps will find your address based on location.

The actual addresses of fixed posts ought to be included in our plans and given to both operators and net controls.

Something to add to a checklist of event to-do's.

Please sign our Warning Petition

Earlier today, I received an e-mail from Art Botterell, one of the world’s leading experts on emergency public warning. He is the father of the Common Alerting Protocol, the global standard for warning messages, and godfather of the improved alerts being sent by broadcasters and cellular carriers.

Please sign the petition.

Here’s the letter:

Hi Friends -

A few of us, led by Richard Rudman, are doing a bit of consciousness-raising.  It’s easy to imagine that having systems like IPAWS solves the warning challenge.  But folks who’ve studied the subject know that one of the biggest obstacles to effective warning is the lack of a consistent professional standard of practice for warning issuance.

Why shouldn’t the whys, whens and wherebys of warning be part of NIMS?  We’re starting with a petition:

Congress should enact legislation for a national strategy so emergency public public information is always coordinated with other emergency response measures using the PPW report, “A National Strategy for Integrated Public Warning and Capability”: www.partnershipforpublicwarning.org/ppw/docs/nationalstrategy.pdf as a basis and guidance.”

That’s why I signed a petition to The United States House of Representatives, The United States Senate, and President Barack Obama, which says:

“Congress should enact legislation for a national strategy so emergency public public information is always coordinated with other emergency response measures. The PPW report, “A National Strategy for Integrated Public Warning and Capability”: www.partnershipforpublicwarning.org/ppw/docs/nationalstrategy.pdf”

Will you sign this petition? Click here:

http://signon.org/sign/the-united-states-needs?source=s.em.mt&r_by=7710354

Thanks!

- Art

Drinking in Uniform, Need I Say More?

Three off-duty members of the local senior police volunteer program showed up at the grocery store's weekly wine tasting tonight. And they tasted.

Care to guess how many calls the PD will get about this? Wonder if they had their police car parked outside?

Remember: Anytime you wear any insignia, you represent that organization. And people judge you and the organization together.

Never be around alcohol when in uniform. Not even to buy a six-pack with $100 of other groceries. Just don't do it.

Switching to Duracell

Because I am not perfect, I am switching from my old favorite Kirkland AA batteries to Duracells, also purchased from Costco.

A friend recently had Costco batteries leak and force early retirement of a piece of gear.

He wanted to see if the equipment might be salvageable so he called Duracell. Thinking it was their batteries that leaked, the Duracell people offered to replace the damaged item. That really bugged him.

See where I am headed? I've had batteries leak in the past. It's been years, but since I have tons of gear and use tons of batteries, the extra money spent on Duracells is a good investment.

I will probably carry Kirkland's as field replacement, but if quick use isn't planned, Duracell it will be.