Transmitter

[dmcole]

Maybe after building a fm02 I will have a greater understanding.

Smooth:

The FM-02 requires no real "building" -- you will have to make an antenna (here's IdenBenHad's how-to on an easy dipole: http://doityourselfchristmas.com/forums/showthread.php?12895-FM02-Transmitter-Setup) and you will need a power supply.

\dmc

[dmcole]

Hi:
The hardware is no problem, the software is.

Ain't that the truth ... and, if anything, I'm more a software guy than a hardware guy (actually, I'm more a word guy than an arithmetic guy, which means I'm neither a hardware guy nor a software guy).

\dmc

[David_AVD]

100mW from my living room to the street (about 100FT) does not give good saturation to all listeners, IF you could place the transmitter at the street, it would be better.

Really? 100mW should get you a lot further than 100 feet! Even 10 mW should do. Maybe the antenna used was woefully inefficient?

[dmcole]

Here is link to origional data sheet for what appears to be the discontinued part...

http://www.xhl.com.cn/ramtron/Si4710_11-A20Rev1_0.pdf


Thanks. There's a similar sheet for the 13 part on the Silicon Labs web site, but I wasn't able to jump through all the hoops they want you to for downloading.



If I were to design a DIY project, I would lean toward a PIC micro that talked to the SI4710 (or equivlent) and using hyperterm, the user could set frequency, RF power, audio levels, and RDS message in non-volitile flash on the PIC (so user would only have to set it up once), and then have LEDs on the PIC to display the high level and low level register for audio levels such that user could see how loud to turn up or down sound from host PC to analog input of RF transmitter. It would have two RCA connectors for left and right stereo inputs of analog audio, It would be powered either by a 5V wall wart or USB cable from PC, and it would have an SMA connecter on the board normalized to 50 ohms so user could attach antenna directly or connect to in-line amp. BTW, Mini-Circuits makes some great in-line RF amps!

This is the project I've been thinking about bringing into the DIYC community:

http://www.mikeyancey.com/FM-Stereo-Broadcaster.php

I wasn't planning to use the Arduino board per se, but would use an ATmega328, the bootloader and existing firmware, which provides a nifty LED digital readout for tuning. Of course, it obviously uses the NS73M, but it appears that the Si4713 is cheaper in quantity and more readily available (i.e.: from Mouser rather than having to go through SparkFun). Also the Si4713 has the RDM and the NS73M does not; my theory was to leverage the various communities to put the RDM stuff through the ATmega328.

But, as I said earlier in this thread, I'm not the guy you want to depend upon to write you software or design you hardware.

\dmc

[IdunBenhad]

Hi:
dmc: I have the App notes and software notes downloaded from Silicon Labs. AN332 is 306 pages long in PDF. The software note is not near that big. I can E:mail them over if you would like to have them. Just PM me with your E:mail address.

Looking into the notes, etc., I think I would rather spend my time on something else. While fooling with this would be fun, I think for my purposes the FM02 is just great. Personally, I wonder if RDS is really worth the effort. It's not to me, although I don't have a RDS capable radio, either. Does one want the viewer to watch his display or the RDS readout?

David_AVD is right. My 30 mw goes 1/2 mile when on a dipole antenna. What more can you ask for?

Work on the antenna, not the power.

[ags0000]

My $0.02 (US): YES! I'd love to be able to have a proven design for FM transmission. My first year (2010) I started about 2 weeks before Christmas and put up an RGB mini-mega tree. It was a blast. I thought that just the "pretty lights" would be wonderful - and they were. It wasn't until I shot a (video only) video, uploaded it to YouTube, and then added a canned soundtrack that I realized how much better the entire experience was with audio as well - synchronized or not. The way I perceive it it's the difference between a "display" and a "show" (lights vs. lights/audio). So, I want music for 2011.

I'd love to see a design with the option of an integrated antenna. IMO if a new design is undertaken, RDS would be worthwhile. Would also like to see digital set/readout of xmit frequency. On-board power regulation is a must. Why require an additional board to enable clean audio? I think of this as a "little black box" that should be like oxygen - you only notice when it's not there. It would be fine to require a wall-wart to connect through a standard jack to the transmitter where that supply is treated for better "quieter" regulation. MOST important, IMO, is the ability to adjust the output gain. I don't want to face Johnny F.C.C. Law on Christmas eve because of illegal operation (or neighbor complaints). Rather than playing games with the dipole antenna in the basement (which I don't have anyway), why not just include the ability to adjust the gain? I'd love to see that.

I'm not sure how much work this would entail, or the difficulty in meeting these "specs". I'm offering a user's POV only.

[dmcole]

@Idun: I think I'll pass on a 306-page app note of which I will probably only understand (optimistically) 30 percent.

@AGS: I remain a philosophical supporter of this project and will do what I can do. Since the preliminary skill needed -- the ability to solder a QFN-20 to a breakout board -- is beyond my skein, I don't think I'm going to be the primary driver here.

\dmc

[ags0000]

Oh, and I forgot the best part, the end-all of arguments for including RDS in the project: With RDS, you could just send out text over the airways with the proper broadcast frequency for listeners to tune to. Then you could ditch all the time, effort, and expense of the "Tune To" signs....

[yes, this is a joke]

[Mactayl]

Oh, and I forgot the best part, the end-all of arguments for including RDS in the project: With RDS, you could just send out text over the airways with the proper broadcast frequency for listeners to tune to. Then you could ditch all the time, effort, and expense of the "Tune To" signs....

[yes, this is a joke]

ROTFLMAO......:lol: