RTL-SDR Reception levels for ATSC Carriers - AVS Forum
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post #1 of 1 Old 01-21-2013, 12:36 PM - Thread Starter
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I recently acquired on EBay a dongle meant for DVB-T reception in Europe but
which works with software as a software defined receiver from 24mHz to 1700 mHz.
(a $12.50 investment, by the way)

I decided to look at the ATSC carrier frequencies of the digital TV stations
using a 440 mhz vertical non-directional antenna mounted atop a 100 foot pine
tree. Here is my result:

RF Channel db above noise
14 30 KTNC-42
15 0 analog 15 received
16 0
17 0
18 30 KUVS-19
19 0 KOFY-20 no signal received on the vertical at
the same time my wife was watching ch 20 on a 20 foot high antenna
20 30 unknown
21 40 KMAX-31
22 0 analog 22 received
23 20 KEZT-23
24 5 unknown
25 40 KOVR-13
26 20 KTFK-64
27 0
28 18 KKPM-65(heterodyne)
29 10 KPIX-5
30 20 KQED-9
31 0
32 30 KEMO-50
33 15 KMTP-32
34 10 KFSF-66
35 18 KCRA-3
36 30 KICU-36
38 10 KRON-4
39 18 KCNS-38
40 30 KTXL-40
41 10 unknown
42 25 KMSX-14 (heterodyne)
43 12 KCSM-60
44 25 KTVU-2
45 25 KBCA-44
46 20 KQCA-58
47 10 unknown
48 30 KSPX-29
49 9 unknown
50 20 KQEH-54
51 25 KBIT-8 (heterodyne)

2 0
3 30 KCSO-33
4 10 unknown
5 0
6 0 6 analog received
7 20 KGO-7 (rapid fading to 10db at about twice
per second. only signal with fading)
8 20 KSBW-8 (heterodyne with Reno 8)
9 30 KVIE-6
10 30 KXTV-10
11 0
12 10 KNTV-11
13 0

Several questions - How far above quieting must an ATSC signal be to be
watchable? Why would KOFY show no signal into a vertical antenna while it is
being watched on a horizontal? KOFY is our most consistent Bay Area channel.
On channels 26, 39, 43, and 47 I noticed another signal of equal strength
27.5kHz above the ATSC carrier {.3375}. Any idea what it is? (Don Hackler has responded on another forum that these are pilot frequency offsets previously required to prevent adjacent channel interference to analog stations that have not yet been disabled).

Since I took these measurements I adjusted the waterfall contrast on the dongle and now see signals just above the noise level on 15, 13(Reno?) and 31. Since this antenna is cut for 440mHz and has zero gain it may be more effective on the low UHF channels and being vertical is probably 20 db or more below what a horizontal antenna would receive. I have a cable on order to adapt my 91XG antenna to the dongle and will be interested to see what quieting level is needed to receive a signal.
Ernie
W6KAP
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