Does anybody know why the Los Angeles basin is so prone to receiving FM/VHF DX particularly from the San Diego and Tijuana region, and seldom anywhere else?
I remember discovering this phenomenon as a kid in the late 1980s when I would occasionally see all the San Diego VHF television stations miraculously booming in on old mechanical rotary tuning knob television sets when my family still owned them -- the kind that didn't allow you to skip over channels while tuning up/down. Never did I see anything appear from the north (Santa Barbara/Ventura). And only weak DX reception would appear from the east (e.g. KVCR-24 would go from "absolutely no signal" to "audio plus a barely-syncing picture"). But that was it. In terms of the big DX signals, those always came only from San Diego/Tijuana.
Anyway, in recent weeks, while using my new DX-286, I noticed XHITZ appearing on 90.3 FM almost every evening. But last night, XHITZ was coming in so well, I decided to do a full FM band scan. The result, using only the DX-286's telescoping antenna, was impressive:
[1] = Don't know how to identify these or their locations
[2] = No radio-locator.com-listed stations' streams matched the audio, presuming these are undatabased X-stations
It seems like there is almost a waveguide-like conduit from San Diego and Tijuana that runs up the coast and dumps out on top of my location -- with some added contributions from points directly east of me, just as was my experience in the late 1980s with the VHF TV band. (Every other station I found during my repeated scans of the dial last night were locals that radio-locator.com showed covered my location in the San Gabriel valley.)
The interesting thing about these catches was that their signals sometimes rapidly faded in and out, much faster than AM skywave fade occurs. Holding the radio perfectly still, some seemed to fade from full strength to nothing in only 1-2 seconds before coming back, as if some sort of inversion layer turbulence might have been causing very rapid changes to their reflection vectors for brief periods. Most of the time, though, each signal's strength was stable and changed only slowly.
I'm not certain whether this is e-skip or tropospheric ducting -- San Diego and Tijuana are only about 120-130 miles from me and that seems quite short for either. But based on the current weather and the time of year, I'm assuming tropospheric propagation.
I remember discovering this phenomenon as a kid in the late 1980s when I would occasionally see all the San Diego VHF television stations miraculously booming in on old mechanical rotary tuning knob television sets when my family still owned them -- the kind that didn't allow you to skip over channels while tuning up/down. Never did I see anything appear from the north (Santa Barbara/Ventura). And only weak DX reception would appear from the east (e.g. KVCR-24 would go from "absolutely no signal" to "audio plus a barely-syncing picture"). But that was it. In terms of the big DX signals, those always came only from San Diego/Tijuana.
Anyway, in recent weeks, while using my new DX-286, I noticed XHITZ appearing on 90.3 FM almost every evening. But last night, XHITZ was coming in so well, I decided to do a full FM band scan. The result, using only the DX-286's telescoping antenna, was impressive:
Code:
FREQ CALL dBu/dB LOCATION
87.7 [1] 36/46 (SPANISH; RELIGION)
87.9 [1] 19/40 (INSTRUMENTAL MUSIC)
88.3 KUCR 12/42 RIVERSIDE
89.1 KUOR 14/43 REDLANDS
89.5 KPBS 22/45 SAN DIEGO
89.7 KSGN 12/42 RIVERSIDE
90.1 KLRD 23/45 SAN BERNARDINO
90.3 XHITZ 15/42 TIJUANA
91.1 KETRA 27/46 TIJUANA
91.7 [2] 15/43 (SPANISH; MAYBE XHGLX-FM?)
91.9 KVCR 15/43 SAN BERNARDINO
92.5 XHRM 16/49 TIJUANA
94.1 KMYI 23/45 SAN DIEGO
94.3 [2] 10/40 (SPANISH)
94.9 KBZT 20/46 SAN DIEGO
96.5 KYXY 23/44 SAN DIEGO
98.1 KXSN 11/42 SAN DIEGO
99.3 XHOCL 9/40 TIJUANA
99.7 XHTY 10/42 TIJUANA
101.5 KGB 11/42 SAN DIEGO
102.9 KLQV 17/40 SAN DIEGO
103.1 KDLE 21/46 NEWPORT BEACH
106.3 KALI 13/43 SANTA ANA[1] = Don't know how to identify these or their locations
[2] = No radio-locator.com-listed stations' streams matched the audio, presuming these are undatabased X-stations
It seems like there is almost a waveguide-like conduit from San Diego and Tijuana that runs up the coast and dumps out on top of my location -- with some added contributions from points directly east of me, just as was my experience in the late 1980s with the VHF TV band. (Every other station I found during my repeated scans of the dial last night were locals that radio-locator.com showed covered my location in the San Gabriel valley.)
The interesting thing about these catches was that their signals sometimes rapidly faded in and out, much faster than AM skywave fade occurs. Holding the radio perfectly still, some seemed to fade from full strength to nothing in only 1-2 seconds before coming back, as if some sort of inversion layer turbulence might have been causing very rapid changes to their reflection vectors for brief periods. Most of the time, though, each signal's strength was stable and changed only slowly.
I'm not certain whether this is e-skip or tropospheric ducting -- San Diego and Tijuana are only about 120-130 miles from me and that seems quite short for either. But based on the current weather and the time of year, I'm assuming tropospheric propagation.
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