Re: W-FM


Russ Hines <russ@...>
 

Well, having worked as a broadcast engineer in the U.S. for nearly the last 30 years, all I can say is... HUH?!?!?� I have no idea what Jose's been smokin', but it must be REALLY good. ;-)

I'm into versatility, but there is such a thing called "mission creep," and I'm guessing that's where this is going.�

For communications purposes, deviation for FM is +/-5kHz is wide, +/- 2.5kHz is narrow.� IMHO, 6kHz should work just dandy for both full-carrier AM and wide FM.

But if you really want to include it, then for U.S. broadcast, the channels for FM are 200kHz wide, max modulating frequency is 15kHz, 100% modulation is +/- 75kHz deviation, and all subcarriers are AM modulated.� For the AM broadcast band, the channels are 10kHz wide, max modulating frequency is about 5kHz.� Now that's assuming you don't incorporate IBOC "HD" radio that you wouldn't be able to include anyway unless you paid a horrendous licensing fee to Ibiquity.

But if you're willing to go that far, how about a incorporating an ATSC/DVB/COFDM/16QAM/64QAM/FLO digital television demod?�

See where mission creep can lead you. ;-)

Simon, your SDR Console is a really nice, useful communications tool for SDR enthusiasts, not a table top radio/stereo/MP3/8-track player/alarm-clock/coffee-maker.� I wouldn't worry trying to make it all things to all people because no one will ever be satisfied, and a once-useful tool with promise will become bloated and impossible to use.

Again, just IMHO.

73,
Russ
WB8ZCC

On 1/4/2011 3:03 PM, jose maria trueba wrote:

�

Hi,

75KHz is the nominal frequency deviation of a FM mono broadcast transmission, but now all of them are using stereo mode, adding two 38KHz sub-carriers. Mode is called 256-f3 because (75dev+38stereo+15max_audio_freq)x2 equals 256, nominal bandwidth.

Later they came with RDS, sub-carrier is at 57KHz, resulting a max bandwidth of� (57+75)x2 equal to 264, and filters should be as wide 280KHz. There are some 330KHz filters to be used in cascade with another one. I imagine that some are that wide to give a margin for some over-deviating transmissions.

Let us say that 280KHz@-6dB is a reasonable bandwidth.

73's
Jose

2011/1/4 Simon HB9DRV <simon@...>
�

Hi,

�

No �I�ll maybe add it very soon but need help!

�

What bandwidths are needed? For broadcast I think it�s 100kHz, anyway let me know what typical bandwidths are needed please.

�

You never know � I may even add stereo J

�

Simon HB9DRV

http://sdr-radio.com

�

From: sdr-radio-com@... [mailto:sdr-radio-com@...] On Behalf Of Rob M0TFO
Sent: 04 January 2011 20:10
To: sdr-radio-com@...
Subject: [sdr-radio-com] W-FM

�

�

I may of just missed it,but does sdr-radio support Wide FM?
Rob


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