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intermod

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Everything posted by intermod

  1. intermod
    It does - maybe like the MD782 models (I have two of them). G
  2. intermod
    Another interesting SFR product: https://www.belfone.com/bf-sfr600-single-frequency-repeater_p66.html Supplier indicates US$398 plus $120 shipping to west coast from China. Greg
  3. intermod
    Jeez...just making a joke on the internet comment...... I have no interest in proving anyone wrong - just providing what someone else noted. I was incorrect on the isolator as you noted- as the RX goes on the (load) port closest to the antenna. So even onmy flawed dual isolator solution, 30 dB is all you get. (A side note - this arrangement might also damage the receiver if the antenna VSWR sucked....). G
  4. intermod
    I read this on internet - so it must have been true: https://cwh050.blogspot.com/2017/01/extended-range-direct-mode.html ______________ Postscript 04.03.17A Circulator cannot be used as it does not offer sufficient isolation (<30dB). - Thanks to Jim for trying this out. Even a negative result is a result. Postscript 30.05.18The SLR1000 has an optional built-in high speed antenna switch that will allow the repeater to be used with a single antenna. The same could be said about the other repeaters but Motorola doesn't produce an antenna switch for them unfortunately. The antenna relay cannot be used as this is an electro-mechanical device that cannot cope with the high speed switching. ______________ Does this switch come standard now, or possibly this info is outdated. They mention the isolator approach - I am guessing this is an internal isolator from Moto? If they get a dual-isolator this will give them 60 dB+, which should be enough. But the switch may be lower cost.
  5. intermod
    DMR SFR mode would ideal for locations with no other co-located repeaters, such as at home or at non-commercial radio sites. And most seem to work with any manufacturers's handheld or vehicle radios. I had considered using Motorola's outdoor repeater (SLR1000) - see: https://www.motorolasolutions.com/en_us/products/mototrbo-systems/infrastructure/slr-1000.html#tabproductinfo This is the only Moto model capable of SFR. I considered this at commercial repeater sites as it mounts outdoors on the roof or tower, and connects to a wall-mounted power supply, eliminating the need for an indoor equipment rack (saving money). You an use one or two antennas. If its a commercial site with combiners, you should likely run separate TX and RX antennas to prevent interference to/from other co-located repeaters transmitting on the low side and receiving on the high side of the channel pairs. But then you likely need bandpass filters, and internal models are not yet available unless you hang them externally on the tower and liberally apply a gallon of RTV. Using a single antenna may also cause issues at combined sites or highly-congested ones. But its 2020, and fewer UHF repeaters actually exist at these sites. Prices: Repeater (street new): $1400 Antenna switch: $300 SFP option: $600 Not including antennas and line. Greg
  6. intermod
    Talk-back is Plan B - we would likely need to be right on top of the receiver with a 50W radio to overcome its transmitter. As these are senior care homes, nobody will let us enter, so we have to coax staff out so we can photograph the equipment and model number. Fixed station - officially, this will be our story; at 15 watts max
  7. intermod
    Hi Keith: Please keep in touch. Our goal in the bay region is to identify the product manufacturer, model number and supplier (usually an Amazon dealer). Pictures of the products label are really helpful. Greg
  8. intermod
    Related to this topic: https://forums.mygmrs.com/topic/1971-san-diegola-600-repeater-owners-ix-from-nxdn-idas-equipped-yacht/?hl=nxdn Vessel just passed by the bay area and started interfering with our 600 repeater again this morning. Yacht is now headed to the Seattle/Port Angeles area today. See this for current position: https://www.marinetr...7/vessel:LONIAN Only seems to effect 600 repeater inputs.
  9. intermod
    If they turn it off when they arrive in port. I did advise them that this is likely to cause IX in every US port. Not related to the rogue "Baby Monitors"..... G
  10. intermod
    A week or two ago we started receiving an IDAS/NXDN beacon on our two 600 repeaters (Oakland and Sunol CA; San Francisco Bay Area) - signal was about -79 dBm into Oakland and -100 dBm into Sunol Peak on 467.600 MHz. This would occur every four seconds, for about one second. There was occasional voice traffic as well. This was trashing most of our users. No FCC ID. What a surprise..... After several days of direction-finding (and avoiding the Oakland protests/riots) we located this station on a Yacht that was in dry dock in Oakland CA. It was part of an on-board trunked or advanced-conventional IDAS/NXDN repeater system for their crew of 24; its a big yacht. Crew was Australian. IDAS RAN=31, TGID 1-148 was common. The yacht staff was cooperative and after testing with them, they agreed to disable the repeater system until the left the bay region (they found direct mode worked just fine). The system was enabled again once they left the bay region for San Diego. They indicated they would have their two-way radio company remove this channel from their repeater system when they were back at home. Repeater owners in southern California might also be affected by this signal on 467.600. Listen to your input channel (place your repeater in carrier squelch temporarily to hear this). If you are affected, let me know and I can provide their cell number to you. Or, if you have IDAS/NXDN, the contact on board is Ryan. Vessel remains in the San Diego area as of now (7/1/2020 3:33 PM). Location: https://www.marinetraffic.com/en/ais/details/ships/shipid:5662034/mmsi:319139700/imo:9800087/vessel:LONIAN
  11. intermod
    That would do it...good solution. I believe that was designed in the repeaters to provide more forgiveness to the UHF mobile radio transmitters that were prone to drifting. But in 1980 things were quite stable. G
  12. intermod
    Directly on the 467 MHz primaries. Listened with various receivers, none have AFC. Last time I saw AFC was on the Micor repeaters, I think. Hope none of those remain in operation...they would be almost 50 years old and sliding back and forth with all the FRS traffic. Some of our users tried to be heard using the same DCS code, but you need to be very close to overcome a 1-5 watt radio in the next room. G
  13. intermod
    Agree that the end-users are actually responsible, but spending time with any one of them to educate / change behavior may not be worth the time. What often happens is that the radios usually ship with the offending frequencies - and they ship hundreds or thousands of these. So the key is to head it off at the supply point. The FCC *will* start sending letters and making phone calls when your information is well-researched and credible.
  14. intermod
    Here in the San Francisco Bay and Sacramento regions we have started hearing a "baby monitor" type devices using GMRS 462 and 467 MHz primary repeater frequencies, in nursing home settings (given the message content). We are aware of about twenty incidents of this over the past three months, but the rate of occurrence is rising. The most recent was strong enough to interfere with a CERT/Fire Council repeater out here. These typically operate during daylight periods, and appear to be continuously keyed for up to 12-16 hours at a time, although background noise, such as televisions, could be keeping them transmitting if set for VOX. They do not have time-out timers enabled. These change channels occasionally, but usually end up on 462.625, 462.725, 467.625 and 467.725 MHz. They use a D754 or a D734 DCS code. This kind of device was explicitly mentioned in past FCC GMRS rulings as it was feared that manufacturer's might use these channels for such things. Given most repeaters here in California are on 1500-4000 ft. mountains, continuous destructive interference will occur to our repeater inputs. I tried to DF the source of one of these last week, but it was found to be in San Francisco and we ran out of time. SF is a particularly difficult place to do this due to the density, hills and other sources. Thankfully these are constantly keyed. The device I was looking for was horizontally polarized, making it about 10-20 dB weaker when received on a vertical vehicle antenna. A Yagi in horizontal worked best. My goal was not to go after the user (they don't know better), but instead get a picture of the device, determine its manufacturer and model number, and establish who is selling it. As these may be used in nursing care facilities, they will likely have to bring the device out to us to be safe. Please let us know here if you hear these as we are trying to keep a list of the channels and codes in use so we can identify the specific radio model. This is clearly in violation of §95.1733(a)(10) and §95.1763© for GMRS, and §95.587(3) for FRS. It also appears to violate §95.533.
  15. intermod
    Well said. Digital will eventually happen. The question is whether we (GMRS licensees) what to propose the rules, or let the manufacturer's propose the rules.
  16. intermod
    dPMR-like 6.25 might have been the approach if no other common digital mode existed. But we have many now. You may have missed the earlier discussions here - interference has to do with signal level & proximity, not technology to any significant degree. And the assumption that the number of users and interference sources would grow and cause overcrowding has no basis. In the end, changes in radio services and rules are always much simpler than you portray. If the Commission simply permitted the typical digital emissions and made no change to analog operations or anything else - new digital radios would operate on existing channel centers. Bandwidth is a don't-care. And like today, if an analog direct-mode operation was interfered with, the victim would simply change channels until it went away. Despite what the Commission believes, I have never seen one user call another and coordinate channel usage (FCC pipe-dream). They can't - they are all in tone squelch, and if they could hear, they would just start spewing expletives at each other. Repeater operations would be the same as they are today - a new repeater owner would usually listen, select a channel, and work with the other co-channel repeater owners to arrive on a good (or least bad) channel. In the beginning, most digital repeaters would be replacing existing analog repeaters - so the interference environment would remain unchanged. Having the option to operate a digital repeater would not necessarily increase the total number of GMRS repeaters. Digital repeaters are expensive enough that I cannot see many going up initially anyway. User equipment is also slightly more expensive. What if a new digital repeater owner does not coordinate? You listen for his (analog) Morse Code IDer, or buy the $90 digital radio with Promiscuous Mode and talk to them directly if you want to save time. Also - all the new digital equipment have an extremely good "busy-channel-lockout" features if it came down to it. But like analog, nobody would want to use it. They would simply move their repeater to a different channel and avoid the headache (and likely jamming/self-policing). Would digital complicate the GMRS? Only for those who wanted to use digital. If I don't want to understand it, then I could save money and just buy analog. Really - its just that simple.
  17. intermod
    That is an interesting idea. You must have seen how public safety maintained backwards-compatibility on their mutual-aid channels (interoperability) when Part 90 users were slowly transitioning to narrowband. They kept them wideband, and did not allow any narrowband operations the 12.5 kHz adjacent channels, until the mutual-aids when narrow. While we are not really going narrow, it would better protect and lock in an analog wideband channel for compatible emergency comms when needed.
  18. intermod
    I am late to the game...just saw this post. Jeez guys, nobody really understood the poster's question. The issue is why would a manufacturer or supplier sell a radio pre-programmed with tone squelch, instead of just carrier squelch? The fact that some may do this was a surprise to me. I just looked up some common "FRS" and GMRS radio models and some in fact come with tone squelch on. This is really a poor idea for the consumer and supplier. It may create incompatibility with other radios and result in poor reviews and a greater number of support calls, and the user can't hear someone if they really need help. (Note: but its also a poor idea to expect to reach someone anyway, but its better than nothing - but only if you run carrier squelch). This is what happens when "drive-by" manufacturers and suppliers get into the game to make a quick buck, then leave the mess with someone else (GMRS licensees) when the profits decline. Like many things in this world, GMRS users used to be a reasonably-trained and disciplined service (not to the level of amateur radio, however). GMRS still is to some degree. But the Commission's goal was to promote the greatest amount of benefit in a given spectrum band. While many in the FCC are aware of the "Tragedy of the Commons" (below), they may believe we are not yet there. But IMO, we are getting really close. It should be our collective goal to push back on this when possible. (https://en.wikipedia.org/wiki/Tragedy_of_the_commons: The tragedy of the commons is a situation in a shared-resource system where individual users, acting independently according to their own self-interest, behave contrary to the common good of all users by depleting or spoiling the shared resource through their collective action.)
  19. intermod
    Its not like I want to program my repeater for their output code, with a long hangtime, and set a recurring Morse Code ID to fire off every 15 minutes at one word per minute..... We used to ask the user who they purchased their radio from, and then deal with that supplier - usually local. So here we may never find who that is in this case. The last time the Commission dealt with this kind if thing, I believe they went after the US sales representative, not the manufacturer. Its the holidays, so I may have time to follow-up with the Commission. This one is relatively easy.
  20. intermod
    Several of us in California (bay area and Sacramento) have become inundated with many unlicensed business users on our repeater outputs. Interestingly, most of these users operate the following: TX/RX 462.600 D455 TX/RX 462.725 D252 While our repeaters can cover them in some cases, there are so many bubblepacks that they are reducing our ability to hear simplex/direct mode traffic or more distant repeaters. None of these users have a callsign, and they are operating wideband (we can tell they are wideband due to their 4-5 kHz deviation and resulting volume; narrowband should be lower volume and 2.5 kHz peak deviation). We reached out to several users who all advised they had "RT15" radios. https://tinyurl.com/tmu48vq A customer posted the frequency listing for this "FRS" radio showing the two DCS codes above (actually the inverted codes; D322 Inverted = D455 Non-Inverted, and D462 Inverted = D252 Non-Inverted). So this confirms the user info. But it has a few problems: Defaulted wideband (essentially creating a GMRS radio) Capable of voice encryption Contains a non-FRS channel (462.825) According to the new rules, radios marketed and Type Certified as FRS cannot operate wideband or have encryption, let alone have a Part 90 channel in them. Of course, when asked, the seller replies that the programming cable is available, and I found the software is downloadable for free. Various violations here: §95.591 Sales of FRS combination radios prohibited. (does wideband make this a GMRS radio??) §95.575 FRS modulation limits (exceeded) §95.587 FRS additional requirements. - (a) Transmit frequency capability. FRS transmitter types must not be capable of transmitting on any frequency or channel other than those listed in §95.563 (462.825??) - (e) Effective September 30, 2019, no person shall manufacture or import hand-held portable radio equipment capable of operating under this subpart (FRS) and other licensed or licensed-by-rule services in this chapter (part 15 unlicensed equipment authorizations are permitted if consistent with part 15 rules). The user manual that was submitted for FCC certification shows 2.5 kHz deviation, no scrambling. The current manual now shows 5 kHz deviation and scrambling. Anyone else getting slammed with these things?
  21. intermod
    Maybe this was my nickname when I first cobbled together two Jobcomm portables with duct tape to make a repeater without using those pesky and expensive filter thingy's back in the 80's....
  22. intermod
    Several comments to Rich's post: - My experience also indicates equipment certification is the #1 issue. The FCC wants to maintain separate control over the GMRS space and manufacturers, and I get that. - I would avoid requesting the use of Part 90 equipment. The petition should instead suggest any new Part 95 certification issues that might be appropriate** - Don't restrict the emissions - include those for all the major technologies (FXE, FXD, F1E, F1D, F1W , F7W) - Address "listen-before-talk", particularly §95.1731 Emergency communications - Attempt to get some manufacturer buy-in (the larger the manufacturer, the better) - Have multiple supporting GMRS groups endorse/support the Petition Operationally, this will allow full-power mobile, control station and repeater operation. But do we drop back to better ensure success, such as: - Propose reduced-power repeater operations initially (i.e., 5 watts TPO for first year or two??) - Propose simplex/direct mode only operation initially? - Operation only on the 462 MHz GMRS interstitials initially - Restrict repeaters to certain GMRS channels initially (yea, can-O-worms...) ** Such as automatic analog/digital decoding for pre-transmission monitoring / listen-before-talk; mandatory analog IDers for repeaters, etc. Encryption, shared use of channels (related to linking) is already addressed in the rules and need not be changed.
  23. intermod
    Radioguy7268 is correct. FB2 would also be fine for a private system. However, the idle chit-chat that is common on GMRS is not actually permitted on the business/industrial service. But in reality, it would never be challenged anyway as nobody really cares (including the Commission).
  24. intermod
    While the commercial approach provides many things (allows DMR, group licensing, encryption, etc.), many repeater groups or clubs would no longer have free or low-cost rent at the repeater site. Most site owners will charge full rent for "commercial" repeaters. It would also impact community service teams like CERT or Fire/Disaster Council groups that rely on the availability of very low cost "bubblepack" radios. Yea, one can now buy $100 Part 90 radios, but once the group's designated "radio guy" decides to retire or leaves, nobody knows how to program the radios, or even understands where to buy them.
  25. intermod
    Agree on the costs. But if you need spectrum in a metro area, 6.25 kHz channels that may be the only thing available. So you just eat the antenna, backup power system and additional rack space and site lease costs. Ouch. TETRA - I forgot to mention this! As GMRS uses 25 kHz wideband channels, that could support TETRA (I think it requires 21k bandwidth, so you would have to convince the FCC to go beyond the 20K GMRS limit; its already been done in Part 90). Four TDMA slots would be more flexible than DMR's two and would further reduce message collisions among different groups. The handheld equipment is also quite nice, but still expensive. Since we have 25 kHz channels, it may be lower cost (considering both the repeater and user equipment) to simply split a GMRS channel in half and place two DMR transmitters there. Normal Channel Center: 462.650 New Lower Channel Center: 462.650 MHz - 0.00625 MHz = 462.64375 MHz New Upper Channel Center: 462.650 + 0.00625 = 462.65625 MHz I just confirmed that the Motorola SLR5700 DMR repeater can be programmed for these channel centers. Not sure about the CCRs. This now provides four repeater timeslots or channels in the place of one wideband analog channel. Hmmm..... Greg
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