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Possible to program a cell phone to broadcast RF?

Discussion in 'Technology' started by JAM1, Feb 15, 2010.

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  1. JAM1

    JAM1 F1 Veteran
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    #1 JAM1, Feb 15, 2010
    Does anyone know (or know some brilliant techie who would know) if it's possible to write a program for a cell phone that would enable it to broadcast a specific RF signal? Perhaps through the CODEC chipset directly or through the RF unit? I'm not looking to permanently alter the normal cell phone signal, only temporarily emit a specific RF signal on user demand. Any input would be greatly appreciated!
     
  2. Jedi

    Jedi Moderator
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    #2 Jedi, Feb 15, 2010
    As an old ham radio guy myself (still licensed actually), I gotta ask WHY? I doubt
    you can get to the necessary firmware to alter what data is sent via the RF section.

    But what is it you want to accomplish?

    Jedi
     
  3. JAM1

    JAM1 F1 Veteran
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    #3 JAM1, Feb 15, 2010
    I've just been noodeling around a couple of business ideas related to RF signals, and I wanted to see if I can use a cell phone as a transmission tool.
     
  4. ylshih

    ylshih Shogun Assassin
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    #4 ylshih, Feb 15, 2010
    Most RF chipsets are frequency agile these days, with broad range bandpass filters for the intended operating range. If your frequency of operation is close to the cellphone bands, it might be doable; but you have a number of other problems: 1) your desired modulation mode may not fit the chipset capabilities, 2) you need an FCC experimental license or STA (Special Temporary Authority) to work in whatever band/frequency you're thinking about (unless you are already licensed for that band and use), 3) you would need to have access to the firmware programming tools for the cellphone and be able to build your own version of the low-level firmware, specifically modifying/adapting the RF driver settings and DSP code (this would not be changing a Java script, a lot of this stuff is done by the cell phone mfr for the cell providers as a pre-certified SDK for the phone). If you don't understand what I just said, then the answer is pretty much "no"; if you did, the answer is probably still, "very hard".
     
  5. Jedi

    Jedi Moderator
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    #5 Jedi, Feb 15, 2010
    One other negative is that you'd have to resubmit to the FCC for "type acceptance"
    before you'd be allowed to market such a device. It's very technical, expensive and
    slow to get this.

    Jedi
     
  6. Fast_ian

    Fast_ian Two Time F1 World Champ

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    #6 Fast_ian, Feb 16, 2010
    Could you do it with Bluetooth?
     
  7. JAM1

    JAM1 F1 Veteran
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    #7 JAM1, Feb 20, 2010
    My thought was to have develop a way to allow a cell phone to switch from normal cell phone bands to emergency bands such as 121.50 or 406Mhz (ie. to act as an Emergency Locator Transmitter). It seems to me that having the ELT capabilities in a cell phone could be a great tool for someone in distress when they are unable to receive a cell signal, because they could still transmit an emergency signal to be located/rescued. Yin was nice enough to PM me with some helpful information that I am looking into; but preliminary research is telling me this type of broadcasting can't be done.
     
  8. ylshih

    ylshih Shogun Assassin
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    #8 ylshih, Feb 21, 2010
    I forgot to mention a couple of other things in my PM.

    Check into the Breitling Emergency. They had some trouble getting their watch certified for the emergency band transmitter that's incorporated into the watch. I recall reading that the emergency services were concerned about false alarms by untrained consumers and put some restrictions on it during the approval process.

    Also, I believe that the emergency services are sized for a certain activity level. I doubt they would be prepared for a 10x, 100x or greater increase in alerts. We've seen stories of citizens dialing 911 because they got into a customer service argument with a Burger King store; the FAA or Coast Guard is not going to want to deal with even one incidence of that!
     
  9. LetsJet

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    #9 LetsJet, Feb 21, 2010
    Joe,

    I like your thinking.....Way to think out of the box.

    I think a dual device might have a market (Though relatively small). Though, technically I think it would require two separate systems. Even the "Emergency" is two separate systems with different batteries.

    Truthfully, as much as I'd like to support you on this I think PLBs should be redundant to a cell phone and be a separate piece of safety equipment. I could just see the tweens with PLBs....
     
  10. LetsJet

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    #10 LetsJet, Feb 21, 2010
    That was years ago....

    The Breitling E is an aviators watch with a built in ELT operating on 121.5mhz. ELTs are for aviation only and that's why you need to sign a release with Breitling when you purchase it.
     
  11. JAM1

    JAM1 F1 Veteran
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    #11 JAM1, Feb 21, 2010
    Last edited: Feb 21, 2010
    In the portion of the waiver you sign with Breitling, the owner also acknowledges false alarms will cost them a $15k fine. I recognize that there would be increased false alarms even with the fines in place, and understand how emergency services would not be happy about the increased volume when it was from these types of events. My idea was to have some level of "security" in place to prevent such issues; perhaps the user would have to enter a code (ie their SS#) to launch the product, and a separate number to activate the emergency signal. I would also wonder if the emergency signal could be activated remotely somehow, so that rescuers could track the person in emergency situations.

    I realize the direct market is quite limited for a product like this. My thought was to design, patent, and licence the technology to cellular service provider (or manufacturer) so they could use it as a marketing tool to sell their service over a competitor's.

    LetsJet. I understand your position that PLBs should be redundant; but I believe there is great value in including the technology in a device so many people already own and have a habit of keeping on/near them all the time.
     

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