While my UHF radio needs currently require the monitoring of several digital channels, my agency and other area agencies on VHF still operate in an analog environment. Accordingly, I am about to transplant a VHF Spectra A7 into a new vehicle (along with a UHF Spectra A9 and an AVA, in which I can monitor area digital channels through my Astro Saber III).
With the impending/much publicized required move to "narrow band technology" for (state/local) public service agencies down the road (or just around the corner?), the thought of upgrading to Astro techology is ever-present, but, I can't be certain that my agency or the others I communicate with will even remain within the bandwidth of the VHF Astro Spectra I would be inclined to purchase. As a result, my inclination is to "stay-put" with my analog equipment. Is this short sighted (any comments/insight into required move to digital).
I totally appreciate and respect what you guys do. In my business, you are our lifeline. I'm more of an "end-user" than a tech, but, over the years (30+ in law enforcement), I've always been very interested in getting the most out of my equipment and ensuring that many of my low-tech to no-tech colleagues get the most out of (or at least don't destroy) theirs. Thanks, again, in advance for your insight./CB
Astro Upgrade/Now or Later???
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In my experience, most times the organizations will utilize the same frequencies for digital as they were for analog, but that may require switching the entire radio fleet over at once. If they are doing it in bits & pieces, then yes, new frequencies may be involved. They would tend to want them several MHz away to avoid interference issues, but generally well within the same bandsplit, since they often times put the old analog channels into the digital radios until such time as the entire fleet has changed. Or, they may not even program digital channels into them until the entire fleet is switched (thus, no new frequencies). You never know, they may even switch to an as-yet-not-built 800MHz SmartZone OmniLink Astro capable system down the road (as happened here) in which case it won't matter what VHF split you use. It's a bit of a gamble, but I think you're better than 50% safe by getting one in your current bandsplit.
Todd
Todd
-
ASTROMODAT
- Posts: 1825
- Joined: Tue Nov 05, 2002 12:32 am
In my opinion, it's a big krapshoot to try to predict the spectrum question you raise for any particular circumstance. For instance, in my area, they just spent $70 million on a new Motorola 800 MHz ASTRO trunked system. With this type of equipment "upgrade," utilizing the existing spectrum is no longer an overwhelming issue as it was in the old days of channelized and assigned 25 kHz spectrum.
One thing for sure is that analog FM is rapidly on its way out (at least in the large Metro areas), and it is extremely and almost amazingly quickly being replaced with digital. Look at cell phones---most cellular carriers have been refusing for some time now to provide service for subscribers with the old analog phones, or they are charging huge premiums for the old fogies that refuse to switch to current technology..
Keep in mind that this is not a static game. If you review the APCO P25 standard, you will see a plan to move from 12.5 kHz FDMA (current mode) to 6.25 kHz TDMA. This may involve another switchout of radio equipment. But, it will be necessary to do this in order to save spectrum. Remember, we are trying to get to 4 simultaneous voice conversations per 25 kHz of protected channel bandwidth, which (according to the phasing steps of P25 standards) will need the TDMA (vs FDMA) mode and 6.25 kHz wide channels.
In your post, you mention MONITORing these various agencies. If that's the case, your safest bet is to buy the Uniden APCO25 scanner, when it becomes available. Supposedly, they should have their digital model ready to go in the next 90 days or more and I just heard that they are going to support 9600 control channel (don't know if this is in the first/initial release or not). The control channel issue may be a big part of the reason for the delay. Anyways, for your listening needs, this would be about one twentieth the cost of buying multiple ASTRO radios.
BTW, you mention ASTRO Sabers----they have been discontinued since last year (2002), so you might want to think about the XTS series radios.
Just My 2 Cents,
Larry
One thing for sure is that analog FM is rapidly on its way out (at least in the large Metro areas), and it is extremely and almost amazingly quickly being replaced with digital. Look at cell phones---most cellular carriers have been refusing for some time now to provide service for subscribers with the old analog phones, or they are charging huge premiums for the old fogies that refuse to switch to current technology..
Keep in mind that this is not a static game. If you review the APCO P25 standard, you will see a plan to move from 12.5 kHz FDMA (current mode) to 6.25 kHz TDMA. This may involve another switchout of radio equipment. But, it will be necessary to do this in order to save spectrum. Remember, we are trying to get to 4 simultaneous voice conversations per 25 kHz of protected channel bandwidth, which (according to the phasing steps of P25 standards) will need the TDMA (vs FDMA) mode and 6.25 kHz wide channels.
In your post, you mention MONITORing these various agencies. If that's the case, your safest bet is to buy the Uniden APCO25 scanner, when it becomes available. Supposedly, they should have their digital model ready to go in the next 90 days or more and I just heard that they are going to support 9600 control channel (don't know if this is in the first/initial release or not). The control channel issue may be a big part of the reason for the delay. Anyways, for your listening needs, this would be about one twentieth the cost of buying multiple ASTRO radios.
BTW, you mention ASTRO Sabers----they have been discontinued since last year (2002), so you might want to think about the XTS series radios.
Just My 2 Cents,
Larry