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Monitoring Radio

Discussion in 'Pro Audio Equipment' started by MacPoPo, May 29, 2005.

  1. MacPoPo

    MacPoPo Guest

    My job requires me to keep track of a few radio stations. Currently, everything is recorded through the video tapes. Then the essential portions are encoded into PC using Cooledit. The sound quality is very bad. Is there any better way to improve the efficency, in tearms of time saving and quality? eg. using a mixer and protools?

    Thank you.

    Mac Popo
  2. anonymous

    anonymous Guests

    Im not joking when I say this...maybe replace the recorder?
    I would have to see it to make that call.
    Try to run the signal through a decent pre-amp and go straight to a tape based format or a hard drive if avail.
    DAT's are good for this sort of thing also. Sounds like you need to split the signal before it goes to the video recorder to get better gain structure for the signal being amplified.
  3. MacPoPo

    MacPoPo Guest

    its that guy again

    Hi "Its That Guy Gain",

    Thanks for your Advice.

    Actually, I was thinking of recording all the radio stations, none stop into the computer, stimulatously at once but I am not sure how to do that.

    I did a studio recording of an ensemble before, using protools and (what I think is a ) mixer. I wish to adopt the method but this time the most challenging part is obviously, that the recording will run 24 hours a day. How do i do about setting it? And with what equipments?

    Thanks for all feedbacks and Advice.
  4. anonymous

    anonymous Guests

    Re: its that guy again

    What? :shock:
    I want to help you but that one blew me away :eek:
  5. dpd

    dpd Active Member

    Well, how good are yours tuners? How much multipath trouble do you have? It's probably impossible with one antenna to get the best quality FM reception on multiple stations. (I assume you are recording FM - otherwise, who cares about the sound? :D) The trick is to steer your antenna to null the interfering signal instead of maximizing the desired signal when faced with poor reception.

    You need to record multiple, independent signals to some recording device. Forget a mixer - you definitely don't want to combine the signals from these stations into one, incomrehensible, mess.

    You are going to need a multi-channel sound card/interface and software that can record all of that in real time.

    That's one hellacious data rate going onto your hard drive if you want full bandwidth audio for multiple simultaneous signals. Do the math:

    Audio bandwidth = 15 Khz (for FM broadcast)
    Sampling Rate = 44.1 KSa/sec (you could lower it, but it won't be a common rate which is a problem)
    Bit Depth = 8 bits (for simple monitoring, you can probably get by with lower dynamic range)
    Stereo = 2 channels

    Data Rate to disc = 44,100 * 2 = 88.2 Kbytes/second per station or, 88.2 K * 3,600 = 317.5 Mbytes/hour per station (for 16 bit data) or 158.8 MB/hr (for 8 bit data)

    Unless you have terabytes of hard disc storage, you are facing a serious storage capacity problem. You sure you can't time-sample the stations (e.g record station A for a period of time, then on to station B, etc)? That would really cut down the storage problem.

    If quality is not a big issue, IMO you need to find a way to bit-reduce the signals in real time going to the hard drive (e.g. mp3 encoders set to some heavy bit reduction). There are encoding cards (some software, too) on the market that will do that for you. Not sure how many simultaneous streams the software will handle.

    Good old analog tape looks pretty good from a storage efficiency perspective, yes? But, you still need to search linearly through the recordings to find the times of interest.

    Tell us more, perhaps we can help you find a workable solution.

    You don't work for the FCC, do you? ;) Advertising company?
  6. Kurt Foster

    Kurt Foster Distinguished Member

    Video tape recorders usually do a pretty good job of recording audio ... especially if they are hi fi. The quality of a VHS stereo hi fi recorder, approaches that of 16 bit digital ...

    I too think the trouble lies elsewhere than in the recorder ... either the reciver or the PCM conversion.
  7. dpd

    dpd Active Member

    We used to record satellite feeds on BetaMax via the Sony PCM-501 (IIRC). Worked fine as long as the tape path was in good shape - otherwise, 'birdies' out the wazoo.
  8. Randyman...

    Randyman... Well-Known Member

    You could also get 2 mono stations at a time on any 2-track device (station#1 = L ; Station #2 = R) unless you need to "Q.C." the stereo spread as well...

    Question - Are there any Multrack programs that will write in MP3 format? If you got a multi-input soundcard with 8 inputs (or however many stations you need to record at once), and the software could encode to multiple MP3 streams in realtime. This would alleviate lots of the HD space requirements you would otherwise run into recording 24/7... Unfortunately, I do not know of any "multitrack" software that writes directly in MP3 format (most write BWave and you can convert to MP3 "offline")...

    Whadoyado (what do you do)? Commercial Recon, or what? Just curious what kind of quality you really need.

  9. MacPoPo

    MacPoPo Guest

    Hi People,
    Thanks for the advice and no, I don't work for the FCC.

    Ealier on, what I meant by multi-track recording, is to have a few radios playing at once, with each station going into mixer (?) as a separate signal (or channel?). Then they are suppose to show up as wav in protools, with each station occupying its own track. Then I will save each track as a separate file. But because the radio plays on non-stop, I don't know if my idea is visible.

    Sorry if I don't make myself clear. I am not very familiar with the technical teams

    As for the quality, it's news not music that I am after. So as long as the sound is not blur, it's acceptable. The video cassette recorder is not producing good sound. Perhaps the tapes are old.
  10. TeddyG

    TeddyG Well-Known Member

    Video tapes under constant use should likely be replaced, like what, every couple of days? Certainly every two or 3 weeks. AND, as video tapes in VHS are now "ancient history", there will be less and less quality available. That and the fact that gunk will build up so badly on the heads the machines themselves won't last long.

    I like your idea of doing it digitally, and maybe you can even figure out some way of doing it yourself. But, if this is your job, and you have some sort of budget(Or can propose one to whomever), I think your best bet would be to look up "monitoring" or "audio logging" methods/software/machines - should be something on the web? Used to be able to buy audio cassette machines, some with built-in radio(!), that would do at least 12 hours on one, normally 90 minute, cassette, using extremely slow speeds and auto-reverse(And they were rather inexpensive). Used to see them in magazines like "Monitoring Times", as ways for short wave and scanner listeners to "keep up" on their favorite stations/services... By now, there is almost certainly something "digital" that does the same thing - maybe even better...

    You are not alone! Obviously, radio stations need to do this, public service agencies need to do this --- as well as the FCC...... And if perfection isn't needed, there should be something out there just right for you, at some sort of reasonable cost...

  11. frob

    frob Well-Known Member

    how many tracks are needed? how many stations are you monitoring, for instance if you are monitoring 4 am talk radio stations you would need at least 4 tracks/chanels on whitch to record. either way it looks like you will either need software that can simotaiusly record, playback and mixdown (export the audio that you want) i think two digital stand alone adat, and a DAW would be the best one adat to record 24/7 and the other to listen back, get points of interest and put that into the DAW for further arhiving.
  12. dpd

    dpd Active Member

    MacPoPo - OK, if you bring everything into a mixer and send the direct outputs of each fader to a DAW, you can assign each fader to a track in the DAW. You are still going to need massive hard drive space to do what you want - especially if you record stereo and full audio bandwidth.
  13. anonymous

    anonymous Guests

    I don't know why I didn't ask this ealier. What kind of cables are being used to provide to signal to the recorder? My guess is coax.
    Is that right? If you can find that info out for me, I most likely can come up with some sort of options to getting a decent quality signal for you to record with.

    Also, trace the wires from where they come out the wall (or where ever) and let me know if they are less than a couple of inches to any 120V (plugs, cords, power strips, ect.)------they can run near the power cords, but not constantly beside them for any distance
    And check to make sure that the cables (the entire length) are in good shape and DO NOT have any splitters, or couplings, or pinched marks on them.
  14. anonymous

    anonymous Guests

  15. Randyman...

    Randyman... Well-Known Member

    Yes - where are these signals fed from?

    You should not "need" a mixer, just a "multiple input soundcard" for your computer. You will feed each seperate Radio Station (line level audio signals) directly into this soundcard. Then, you would open your software, and "assign" each radio station's connection to a seperate computer track. Then, you will have all of the stations recorded discretely on your Computer for playback at a later time. You could even burn CD's + etc from this audio data.

    Like I mentioned above, recording multiple streams 24/7 is going to eat up LOTS and LOTS of hard drive space. I am still not sure of any Audio Software that would write directly in MP3 format, but that would help reduce the file sizes. This would save TONS of room on the HD with acceptable quality loss (depending on your quality needs - we still don't know what you need this stuf for, or what kind of quality you need).

    That's all I got until we get more details...

  16. dpd

    dpd Active Member

    I can find dozens of mp3 recorders for the PC but not anything (yet) that does it with hardware for multiple channels. I guess if you have a fast enough PC and drive you may be able to run multiple instances of the software. Most of it is freeware or cheapware. Google 'mp3 recorder' and have at it. Good luck
  17. frob

    frob Well-Known Member

    the problem with running it more than one instance on the same daw would be that, each instance would fight for control oven the hardware.
  18. dpd

    dpd Active Member

    ^^^ yeesh - what was I thinking? I tried to find a PCI card that did the mp3 encoding in real time for multiple channels, but didn't find anything.
  19. frob

    frob Well-Known Member

    i dont think you would find any hardware like that. best bet might even build a custom lynux box and run some kind of freeware program, mite be a bit too dificult but it would definatly be cheap. speaking of freeware try download.com you mite find somthing that does that.

    i still think that the bigest problem would be recording NONSTOP and editing in the same box.
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