C4FM Thing of the past or of the future?

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by N7BKV, Jun 22, 2019.

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  1. N7BKV

    N7BKV Ham Member QRZ Page

    So I am wanting to keep radio radio and not do radio over internet or internet through the radio.
    Does C4FM have a place here? Or is it's usefulness only with internet?

    I am looking at getting a Yaesu FTM-7250DR mobile rig with C4FM capability with auto mode switching to invoke the mode when applicable.

    It this a good and useful thing? Or is it just Yaesu's fight to be the king of the mode hill?

    I am quite ignorant of all the various brands' mode dominance competitions. Just don't want to buy a technology that will be left in the dust in the near future.

    C4FM opinions of all kinds welcome.


    Brian N
  2. K8ERV

    K8ERV Ham Member QRZ Page

    What is C4FM?

    TOM K8ERV Montrose Colo
    K0UO likes this.
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I think it's when you use C4 to blow up an FM rig.:cool:
    WA9SVD, K0UO, K2WH and 3 others like this.
  4. WB2LBV

    WB2LBV Ham Member QRZ Page

    One of the features/capabilities of all of the digital voice modes (C4FM/Fusion, D-Star, DMR) is the possibility of internet linking to extend communication range beyond normal simplex or repeater operation. Even if you only use RF to access repeaters with these modes there will probably be other stations on the same systems using internet linking.
    As for whether a C4FM mobile will be useful for you, the answer will depend on how many Fusion repeaters are active in the area(s) where you normally operate. If there aren't that many (or none) then the 7250 would probably be a waste of money for you since it doesn't look like you are interested in using a hotspot as a substitute for repeaters.
    N7BKV likes this.
  5. K6CLS

    K6CLS Ham Member QRZ Page

    I think underlying your question is the fact that Yaesu doesn't offer a model like my FT7900 - 2 band 50w mobile no frills FM only. All their new models have C4FM and Fusion built in. Same with Icom,ball radios have D-zast-Star built in.

    Consider either Alinco DR735, or Kenwood TM-V71.

    The digital voice mode is a different question. Find out what mode has the most activity in your area, and choose a model offering that. For me, seems like DMR is the front-runner.
  6. KF5LJW

    KF5LJW Ham Member QRZ Page

    Seriously doubt C4FM aka FDMA wins out of the digital modes, but with absolute certainty a digital mode will take over as it has already done on the commercial and public safety side with good reasons. The top four reasons are:

    1. Spectral Efficiency
    2. High Speed Data
    3. Battery efficiency for battery operated HT's
    4. Interoperability

    Conventional FM just cannot compete. As of today Public Safety, military, and utilities have all but completely abandoned conventional FM and use EDAC's, P25 Phase 1, and all migrating to P25 Phase 2.

    EDACs and P25 Phase 1 use C4FM a FDMA modulation is a 12.5 Khz or half that of conventional FM allowing twice the amount of channels. P25 Phase 1 can be either Voice or Data with very high error correction. P25 Phase 2 still uses the same 12.5 Khz bandwidth but TDMA allows for 2-voice channels (6.25 Khz), 1 voice plus data, or high speed data.

    Being digital modulation uses less power thus extending battery life especially important with HT's and towers when power is knocked out.

    Interoperability is a huge benefit. I currently work for a very large electric utility designing a massive P25 Phase 2 system that cover 9 states with over 220 towers and unknown number of mobiles and HT's in the thousands. Not only can any radio talk to any other radio anywhere on any frequency band, all can talk to local police, sheriff, fire, gas utility, water utility and Homeland Security.

    Here is the real threat digital VHF and UHF repeaters bring to hams, or the delight if you are a younger ham hungry for modern technology, is it can replace all that expensive HF space robbing equipment allowing you to talk to anyone, anywhere, anytime with data with nothing more than a inexpensive HT like a CELL PHONE already does. Heck you do no teven need a HT on the commercial side, any cell phone will work with BeOn app. You may not like that, but can save the hobby and bring youth back to an antiquated hobby. Doubt it will be C4FM. but it will all be digital sooner than you think. Just gotta wait for the winner modulation to surface be it D-Star, DMR, C4FM, TDMA or some other unknown modulation. One thing for sure is convention FM days are numbered.
    Last edited: Jun 23, 2019
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  7. KF5LJW

    KF5LJW Ham Member QRZ Page

    Forgot one important point. As for which digital mode you use today is a pretty simple decision. Look at a repeater directory and see what modes there are in your area. Fusion seems to be falling off a cliff in a lot of areas. So if there is mostly D-Star and no Fusion, you are not going to be a Happy Camper stuck with an expensive Fusion capable conventional FM radio.

    Not certain, but I think most Yaesu C4FM radios are Auto mode. Check it out and not limit yourself to one Yeasu model. In my area D-Star is the best choice, secon dis DMR, and Fusion is a No Go.
    K0UO and N7BKV like this.
  8. N7BKV

    N7BKV Ham Member QRZ Page

    This addresses the core of my concern behind my original post.

    Only time will tell. And a lot of hardware will get shelved along the way.
  9. AI3V

    AI3V Ham Member QRZ Page

    Let me translate this for you.

    "We have a radio here that uses a modulation scheme all our own,and no other radio manufacturer can make one without paying us a royalty.

    We need our salesmen to convince some mayor that the guy digging the ditch for the overpass drain would somehow have a need to talk to a detective 3 states over, so talk about homeland security.

    If we pull this off, we can sell tens of thousands of radios at several thousand dollars a pop, and buy a new boat."

    NK8I, WD4IGX, 2E0JTP and 7 others like this.
  10. K7JEM

    K7JEM Ham Member QRZ Page

    "Narrow" mode FM uses the same 12.5KHz channels, although it technically uses more bandwidth than a C4FM transmission would use. This narrow mode was mandated for most commercial two way users several years ago, and has been used on the 900MHz band for several decades, so it is nothing new. It has been available on most commercial two way radios for around 20 years or so.

    How does the digital modulation extend battery life? FDMA modes use constantly keyed transmitters, same as FM, so TX current draw should be the same. On RX, I don't think there would be a whole lot of difference, probably the digital would require more current, simply because more circuitry is involved to do the D/A processing, etc.

    Now, DMR and other TDMA may offer some TX power advantages, since the actual PA is only running less than 50% of the time, but you're making it sound like simply being "digital modulation" creates an inherent power savings, which it does not.
    WD4IGX and AI7PM like this.

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