Astro Spectra Narrow band?
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Astro Spectra Narrow band?
i got my hands on an Astro Spectra with IMBE, DES/XL/OFB in it... does it have 12.5khz spacing... is that allways included, or allways necessary with IMBE?
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Astro Spectra
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- Joined: Sat Sep 22, 2001 4:00 pm
Re: Astro Spectra Narrow band?
Always included.
Re: Astro Spectra Narrow band?
Not necessarily.
Is this a VHF Astro *Spectra*? I presume the OP is looking for 2.5 spacing for the new narrowband channels? In that case, it is NOT always included - only newer units with higher-stability RF decks will work.
Is this a VHF Astro *Spectra*? I presume the OP is looking for 2.5 spacing for the new narrowband channels? In that case, it is NOT always included - only newer units with higher-stability RF decks will work.
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Astro Spectra
- Posts: 669
- Joined: Sat Sep 22, 2001 4:00 pm
Re: Astro Spectra Narrow band?
I read the question as refering to 12.5 kHz bandwidth not 2.5 kHz synthesizer step…
But to clarify all Astro products do both 25 and 12.5 kHz channels (actual receiver IF bandwidths are approx 16 and 8 kHz respectively) but only newer radios can have the frequency set in 2.5 kHz increments.
As to the second part of the question, the C4FM modulation used on most P25 systems fits in a 12.5 kHz wide channel.
But to clarify all Astro products do both 25 and 12.5 kHz channels (actual receiver IF bandwidths are approx 16 and 8 kHz respectively) but only newer radios can have the frequency set in 2.5 kHz increments.
As to the second part of the question, the C4FM modulation used on most P25 systems fits in a 12.5 kHz wide channel.
Re: Astro Spectra Narrow band?
ok, now you guys have me totally confused, and it may just be because im reading this at 2am.
my previous non-astro spectra could do the frequencies in the T band, which ended in 5125, 9125, etc... to add 5khz to a frequency of 477,912,500hz would be 477,917,500hz, as apposed to 477,915,000hz if one were to add 2.5khz?
you're right when im referring to the frequency bandwidth of 25khz vs 12.5khz, and im pretty sure that the radio was previously operating on a frequency i know to work with the 477.9125mhz range for example, just checking that i would be able to operate on the frequency in 12.5khz bandwidth...
thx...
my previous non-astro spectra could do the frequencies in the T band, which ended in 5125, 9125, etc... to add 5khz to a frequency of 477,912,500hz would be 477,917,500hz, as apposed to 477,915,000hz if one were to add 2.5khz?
you're right when im referring to the frequency bandwidth of 25khz vs 12.5khz, and im pretty sure that the radio was previously operating on a frequency i know to work with the 477.9125mhz range for example, just checking that i would be able to operate on the frequency in 12.5khz bandwidth...
thx...
Re: Astro Spectra Narrow band?
Well since I'm writing this at 5am, I may or may not be much better off, but I'll give it a go...
My understanding is that all Astro Spectras will allow channel deviations in either 5KHz or 2.5KHz, however, some older units could only cope with 25KHz spaced channels, and not with 12.5KHz spaced channels. I also want to say that this was only a problem on the VHF side, though I don't know for certian if this is true. I've been told that if the CPS detects that you are trying to program a 12.5KHz spaced channel into a radio that does not have support for it, it will throw out a warning.
Hopefully this clears things up a bit.
My understanding is that all Astro Spectras will allow channel deviations in either 5KHz or 2.5KHz, however, some older units could only cope with 25KHz spaced channels, and not with 12.5KHz spaced channels. I also want to say that this was only a problem on the VHF side, though I don't know for certian if this is true. I've been told that if the CPS detects that you are trying to program a 12.5KHz spaced channel into a radio that does not have support for it, it will throw out a warning.
Hopefully this clears things up a bit.
Re: Astro Spectra Narrow band?
it does, thanks.. i'll give it a try on the cps when i get a proper programming cable...
on a side note, i've seen some aftermarket prog cables that have the rear connector to rib + 3 leads +power -power and +speaker? what do they use for -speaker?
on a side note, i've seen some aftermarket prog cables that have the rear connector to rib + 3 leads +power -power and +speaker? what do they use for -speaker?