92kHz SCA on an HD Station
One last post of the evening. I don’t know how I missed this, but it is quite a story. I will only put the highlights in.
We have a client on a 92kHz SCA. I am not a fan of doing this in a competitive market, especially this one, but money talks. While doing the HD installation, and the reason I needed a good modulation monitor, the client called within an hour of us turning on the digital carriers. NOISE. That’s all they could say. From all my spectrum analysis I was not able to determine what the deal was. I obtained one of their cheap radios and tested. Sure enough it was gone. Was I missing something? I obtained a modified FMeXtra Aruba radio so I can use that as a base. Way worse.
I made a couple of calls the the Radio Doctor, Lyle Henry, to pick his brains and maybe commission him to fill in the blanks. Well, last week he was all ready to come down and I said to wait as I was going to double check everything and meet with the client to really compare the apples with the apples this time. The day before I spent about an hour verifying all the parameters. I even decided to give the client a bit more injection above what our contract was written. (all I can say is I did not write this thing and we will leave it at that.) I tweaked the Modulation Sciences SCA generator. These guys are not getting what they are paying for and then some.
The next day we met outside the client’s offices. They were late. I turned on the digital carriers. We walked their building with their cheap radio. We ran the Aruba from the back of the car. We were quite amazed that the changes I did the day before made for a better quality signal for them. The client arrived and asked them to listen. They liked what they heard and that is when we told them the digital was on.
“oh, hear the noise?” they exclaimed. I explained to them that everyone has this noise, and believe me the noise was not that bad. It was a hash sound, by the way. I proceeded to take our secret weapon, the Aruba, and tune to another station running HD and a 92kHz SCA. Same noise, even worse. We tuned to our sister station with a 67kHz SCA. Same noise crappy audio. (don’t ask, it’s what we get from them.) Then came the icing, the car SCA tuner the client uses. After a little exchange, the answer is it was just fine. We won them over, and HD is still on today.
Overall, yes there is a hash noise that is very noticeable on the SCA’s when the digital carriers are on. Injection is very important at this point in the game. Also allowing them to modulate the full or close to full 7kHz deviation is a good thing. It all ties in and it all works. Thanks Radio Doctor for your insight. I would not recommend an analog SCA on an HD station, but it can be done. It’s old technology meshing with new. Go new and use FMeXtra or wait until we can sell secondary services on HD3, HD4, or whatever.
I still do not like HD. Seems to be quite a headache. A bitch to deal with. A pain if you have to use older software on a newer box. (That’s a whole other story that I cannot discuss quite yet.)
Tech Notes from the Field 
Do you have any information where I can buy a large amount of FMeXTRA radios? I have look every where and none of the distributor in the US have them. Any information in china? Vucast is no help. Thanks for any information. We have a few radio station in the US and Canada broadcasting in the sub-carrier frequency, but we will like to implement FMeXTRA, we can find the encoders, but no radio is been made it appears.
Wow. A very interesting question. I started to do the standard Google search, as you must have done already, and have found very little to nothing on the subject of the FMeXtra. This may require some deeper digging, but it does not look promising. I do not use FMeXtra, but I did acquire two Aruba radios from a sister station for monitoring the SCA’s. I cannot even find a source for the radios. You can find SCA receivers, Bext (www.bext.com), sells a 210 receiver with an SCA decoder option. You can find inexpensive consumer SCA receivers from places like Metrosonix (www.metrosonix.com), but these do not look like they do FMeXtra. I’ve lost contact with the engineer that worked extensively with FMeXtra, so I do not even know what is happening in that arena today.
If I can find information I will pass it along. So far it is not looking promising.
Regards,
Bill
Hello Bill,
Any luck finding information regarding FMeXtra receivers? Bext have limited numbers of them. Thanks in advance for any information you can give me.
Good morning.
The FMeXtra receivers work well. No noise, well some, but not like the cheap SCA tuners out there. At -16 dBc the noise has become noticeable again, so a readjustment on injection levels are needed. The unfortunate thing is there is no real market for this service. Or client is asking about going on an HD channel. Some pros and many cons in ding that.
If you need a good SCA receiver, grab the FMeXtra.
Cheers,
Bill