Lscott
-
Posts
2918 -
Joined
-
Last visited
-
Days Won
99
Content Type
Profiles
Forums
Events
Gallery
Classifieds
Posts posted by Lscott
-
-
The attached paper was published in an engineering journal. It goes a bit more into the details of narrow verses wide band FM. The material isn't for the "casual" reader.
-
1 hour ago, WRYS709 said:
Did he say where he got it from?
Not specifically, but I think it was Amazon.
-
6 hours ago, WRYS709 said:
Seems like the Cotre C001D has now disappeared off of Amazon completely; not even available for $35 anymore!
Maybe it was all a dream?!
A buddy got one the other day. He said he still needed to install the software to program the radio. He did comment about the funky stud type antenna port.
-
Oh, if you want to find out what is on the various frequencies using the main digital modes, DMR - P25 - NXDN, this site linked below is a good source.
-
6 minutes ago, WSAA635 said:
I'd like it to be able to scan 460MHz(DPS/Highway Patrol) channels so I can keep track of what's going on while driving.
Now days most of the public safety stuff has moved to 700/800 MHz and typical is digital, P25, and maybe using encryption. You may find a few cities that have remained on 450 to 470 MHz narrow FM. There is a lot less to monitor. I have seen some movement where legislation is being proposed to at least prohibit encryption on the public safety frequencies. That's likely to go nowhere.
-
1 hour ago, nokones said:
After the system I was involved with during the narrowband changeover, we did not have any issues as most have described with their experiences. All of our systems were designed with overlapping coverage for redundancy with simulcast, and voting receivers. There could have been some propagation differences but it didn't impact operations.
Even the difference in the audio quality was negligible. I guess when you use quality radios you don't experience those issues.
Those people were lucky. Several posts in other forum sites users reported noticeable reduction in range. I guess it all depended on the original system design before the changes.
-
26 minutes ago, nokones said:
That would be the Vibrasponder Reed, the bigger Reed of the two reeds.
Thanks. I found some info on those now that I have a name for it.
-
21 minutes ago, Sbsyncro said:
But doesn't this only apply to *transmitting* and not to receiving? In other words the HT was RECEIVING signals that were being transmitted by a 15w radio and ghost antenna and a 50w radio with a 1/4 wave mag mount antenna on a big ground plane. (the latter came in much more clearly than the former).
Antennas are symmetrical devices. They receive about the same as they transmit.
-
35 minutes ago, WRXB215 said:
I thought those were racing stripes.
Yup. You "race" away as fast as you can from the black squirrel with the white strip on its back, not towards it.
-
Using a high gain antenna the radiation pattern tends to be flat like a pancake. This concentrates most of the power out horizontally at a 90 degree angle to the antenna. What I suspect is happening is most of the RF power is simply shooting over their heads or hitting the canyon walls.
The HT antenna radiation pattern is more like a fat donut. A lot of the power is at much higher and lower angles relative to the 90 degree position. This allows you to get a signal to and from other stations at much different horizontal elevations.
What some people do is carry several antennas then swap them out depending on local terrain. A high gain antenna is great for open flat country. A low gain, typically a 1/4 wave like what is commonly found on HT's, when in hilly or mountainous areas.
-
17 minutes ago, wrci350 said:
Yeah that's what I was thinking. I know around here there are a bunch of folks using Motorola radios, which probably aren't Part 95 certified, on the GMRS repeaters. You can always tell by that nice Motorola "burst" at the end of their transmissions.
It doesn't really serve a useful purpose in GMRS without the special equipment, but does identify one as a Motorola radio user much like the white strip down the back of a sunk.
-
40 minutes ago, wrci350 said:
The short answer is, "There are no currently-produced 'certified' GMRS radios that have MDC1200". Would you not agree?
That's likely true. Myself I don't know of any.
Those repeater owners that use MDC1200 tend to get labeled as Motorola snobs since that company originally had the patent on the signaling method. It mostly limited the repeater access to users with Motorola radios.
-
1 minute ago, Sshannon said:
How did they get the timing right?
If the squelch tone was sent continuously during the transmission, reed stays sync'd, by inverting the signal at the end would generate a 180 phase shift bucking the original one.
How it's done now I don't know. Everything is done by micro's now with the magic in the software.
-
22 minutes ago, RayP said:
Somewhere along the line, land mobile radio companies decided that the squelch tail was annoying and should be eliminated. Various technical solutions were employed to make the squelch tail go away, to include Motorola's "reverse burst" which inverted or otherwise altered the PL tone for a split second when a transmitter unkeyed.
Just as a side note I read why it's a reverse phase.
The old equipment used a vibrating reed as a filter to open the squelch. This was a mechanical filter basically. The reed was "tuned" to the desired PL frequency. When the transmission stopped it took a bit of time for the reed to stop vibrating and the squelch to close.
The reverse phase, same PL frequency, was sent at the end of the transmission which bucked the reed's vibration which quickly cased it to damp out and stop. Thus the squelch would close faster mostly eliminating the squelch tail.
-
2 hours ago, wrci350 said:
Interesting. Which GMRS type-accepted radios do MDC1200?
A GMRS radio is "certified", the new term, under Part 95E. There are some older commercial radios that have Part 95 certification and are legal to use so long as they are programmed with the correct frequencies, bandwidth and power.
One such example is attached. The radio is both analog FM and digital enabled for P25 Phase 1, however digital is not allowed under current FCC GMRS rules so that part can't be used. Other than that the analog section is just fine, and as you can see in the brochure it does MDC1200.
You can verify the certification by looking at the bottom of the brochure for they type one UHF radio and referencing the FCC ID. Then compare it to the one in the FCC grant. Part 95A was the GMRS rules section before the FCC reorganized Part 95 in 2017. The radio still retains it's certification.
I personally have a few of these radios in my collection.
-
On 2/12/2024 at 6:29 AM, nokones said:
Personally, I would like to see the FCC mandate that the GMRS channel operate on narrowband channels. If it works for Part 90 radio services it can work for Part 95 radio services.
Narrowband emissions help facilitate spectrum efficiency and minimize adjacent channel interference.
The narrow band won't help with spectrum efficiency unless the FCC was going to add more channels to GMRS, which likely won't happen.
The channel interference part is beneficial. There are some interstitial channels that can cause interference to the adjacent main channels. If all of the channels were made narrow band the guard band between them would be greater.
The down side to narrow band is the range reduction. Many Part 90 users found that out quickly when the FCC mandated narrow band for that service group.
Be careful what you wish for.
-
-
24 minutes ago, 73blazer said:
Either it's bleeding over or someone misconfigured a repeater somewhere, or someone purposely linked HAM to a GMRS channel?
Or it could simply be a Ham who setup his own GMRS repeater, just like a bunch of other people ask to do. It seems to be a common topic on this forum.
-
15 minutes ago, WRXB215 said:
Won't be in that area but thanks for pointing this out. 94% in Houston but we may travel up to my son's house in Proctor where it will be 100%.
I traveled with a buddy and his family to see the last one a few years ago. It was an awesome experience. Had some good QSO's with a few Hams on the air during the trip who also happened to be looking for a good place to view the eclipse. All-in-all it was about a 20 hour round trip.
On the way back the traffic was very heavy on the expressways. Stopped for a bite to eat at a Tocco Bell. They were closed. Ran out of food was the note in the door! Really?!
-
I’m checking with some buddies to see who is interested in traveling to the Toledo/Lima Ohio area on April 8 to watch the total lunar eclipse.
https://www.timeanddate.com/eclipse/in/usa/toledo?iso=20240408Anybody around that area planing on going to watch?
-
-
Are both radios the same hardware revision's? If you used the wrong firmware for the hardware version that can bugger up the radio.
-
-
9 hours ago, WSAN654 said:
Hi anyone know anyone who fixes radios within a 50 mile radius of canyon lake, my preference is a store
for GMRS and HAM radio
Thank you
Don't forget there is usually a minimum charge even if it doesn't get fixed. The Kenwood repair depot I've used a few times charges about $120 minimum for repairs for bench time. They do go through the radio and check out the performance and perform an alignment if necessary in addition to whatever the original issue was to fix. The turn around time including shipping is about two to two and a half weeks.
Super Cheap Chinese DMR Radios, Experience?
in Equipment Reviews
Posted
That was the model I saw being recommended. I have some non display Kenwood radio models in my collection. Nice radios but not very convenient use. With up to 32 channels on some of them trying to remember what channel is programmed for what isn't easy if you don't use it very regularly. That's why my preference are the display models.