Kitz Forum
Broadband Related => Broadband Technology => Topic started by: burakkucat on December 24, 2013, 12:28:40 AM
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When first made available, ADSL used frequencies up to 1.1 MHz.
Subsequent enhancements gave ADSL2 and ADSL2+, the latter using frequencies up to 2.2 MHz.
More recent developments have brought VDSL2, initially using frequencies up to 8 MHz and currently using frequencies up to 17 MHz.
Profile 30, using frequencies up to 30 MHz, has not (as of yet) been implemented here in the UK.
Unfortunately for xDSL technology, those ranges of frequencies have have authorised, licensed, uses. Apart from the BBC's Droitwich transmitter (http://en.wikipedia.org/wiki/Droitwich_transmitting_station) (located in the outskirts of the village Wychbold) which broadcasts on 198 kHz and affects virtually every UK xDSL circuit (that spike centred at tones 45 - 46 of our QLN graphs), the other (licensed) sources which occasionally affect xDSL circuits are the high frequency amateur radio bands.
So for reference, here follows a table of the international HF amateur radio bands --
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Very useful to have an up to date list, also there are liable to be domestic allocations about 5 MHz i.e different from country to country.
At least ADSL/VDSL is not saddled with TV's almost pathological fear of filters :- " They cause Group Delay variation !!!! " I remeber a TV masthead pre-amp covering all entertainment bands flat from 40-1000 MHz-. As Southern ATC's radar beamed about 25MW ERP at it every 7 sec, blacking it out for 1/2 sec, filters became essential !
Happy Christmas !
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Not to sure if my QLN graph is showing signs of Radio Interference on VDSL2, I am sure the second one in blue at 1.650Mhz is causeing problems as the tones are missing from 1.650Mhz to 1.750Mhz.
Any clues to which station is affecting the tones.
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. . . I am sure the second one in blue at 1.650Mhz is causeing problems as the tones are missing from 1.650Mhz to 1.750Mhz.
Haven't you misinterpreted your graph? :-\
The X-axis is individual tones, each one of which is 4.3125 kHz wide.
So to calculate the frequency of any particular spike, use the formula f = ((tone number x 4.3125) + 2.15625) kHz.
So that broad hump which you have flagged with the blue pin is between tones 1650 & 1750 (approximately).
Hence fmin = ((1650 x 4.3125) + 2.15625) kHz = 7117.8 kHz
and fmax = ((1750 x 4.3125) + 2.15625) kHz = 7549 kHz.
The origin of that RFI? :shrug2:
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. . . I am sure the second one in blue at 1.650Mhz is causeing problems as the tones are missing from 1.650Mhz to 1.750Mhz.
Haven't you misinterpreted your graph? :-\
Yes I have :-[ but thought the X Axis was 0 to 4000KHz (0 to 4 Mhz) and was not aware you needed an extra calculation formula to arrive at the destination.
Thats excellent BC now I can fully understand the QLN graph now the next will be BIT swaping I must have that misinterpreted to :-\
I do Whish BaldEagle & you had made a 300 page manual on how to Interpret the HG612stats graphs :D
EDIT checked the multiband scanner and getting a radio station on 7280 Khz AM (7.280 Mhz) it driffs in strong to 8 bars signal strength then driffs off to 0 and comes back again over 3 minutes
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I do Whish BaldEagle & you had made a 300 page manual on how to Interpret the HG612stats graphs :D
Our Analytical Eagle has essentially developed such a guide from first principles, whilst instructing Plusnet and using (what was) his defective VDSL2 service as an example! ;)
EDIT checked the multiband scanner and getting a radio station on 7280 Khz AM (7.280 Mhz) it driffs in strong to 8 bars signal strength then driffs off to 0 and comes back again over 3 minutes
It won't be any use for such a higher frequency as 7.280 MHz but here is the link (http://www.mediumwaveradio.com/uk.php) to the site that shows all LF & MF broadcast transmitters in the UK. That frequency band is used here (http://www.hamradioelpaso.com/hf-nets) and here (http://home.earthlink.net/~bscottmd/nts_la.htm), for example, on the North American continent but I don't think those signals are troubling you. :no:
An example of QLN graph analysis.
I am currently using a Huawei HG622 in ADSL2 mode. Hence tones 0 to 255 can be examined. Here is the raw data --
0 -150.0000
1 -150.0000
2 -150.0000
3 -150.0000
4 -150.0000
5 -150.0000
6 -119.5000
7 -116.5000
8 -116.5000
9 -116.0000
10 -117.0000
11 -117.0000
12 -117.5000
13 -117.5000
14 -118.5000
15 -117.0000
16 -117.5000
17 -118.0000
18 -117.5000
19 -118.5000
20 -118.5000
21 -118.0000
22 -118.5000
23 -118.0000
24 -119.5000
25 -119.0000
26 -120.0000
27 -120.5000
28 -120.0000
29 -119.0000
30 -118.0000
31 -116.5000
32 -150.5000
33 -139.0000
34 -141.0000
35 -140.5000
36 -140.5000
37 -137.5000
38 -135.5000
39 -136.0000
40 -135.5000
41 -133.5000
42 -131.0000
43 -131.0000
44 -130.0000
45 -129.5000
46 -116.5000
47 -130.0000
48 -130.0000
49 -130.0000
50 -131.0000
51 -131.0000
52 -131.0000
53 -131.0000
54 -131.5000
55 -132.5000
56 -131.0000
57 -131.5000
58 -130.5000
59 -131.0000
60 -131.5000
61 -131.0000
62 -131.5000
63 -130.5000
64 -131.0000
65 -131.5000
66 -131.0000
67 -131.0000
68 -130.5000
69 -130.5000
70 -131.0000
71 -131.5000
72 -131.0000
73 -130.5000
74 -131.5000
75 -131.0000
76 -130.5000
77 -131.0000
78 -131.0000
79 -131.5000
80 -131.5000
81 -131.5000
82 -131.5000
83 -132.0000
84 -132.0000
85 -131.5000
86 -132.5000
87 -132.0000
88 -131.5000
89 -132.0000
90 -132.5000
91 -132.0000
92 -132.0000
93 -132.0000
94 -131.5000
95 -132.5000
96 -132.5000
97 -132.5000
98 -132.0000
99 -132.5000
100 -132.0000
101 -133.5000
102 -132.0000
103 -133.0000
104 -133.0000
105 -132.5000
106 -132.5000
107 -132.0000
108 -131.5000
109 -133.0000
110 -134.0000
111 -132.5000
112 -133.5000
113 -133.5000
114 -133.0000
115 -132.5000
116 -133.0000
117 -132.5000
118 -132.5000
119 -132.5000
120 -133.5000
121 -132.5000
122 -132.0000
123 -133.0000
124 -133.5000
125 -127.5000
126 -132.5000
127 -129.5000
128 -132.0000
129 -133.0000
130 -133.0000
131 -134.5000
132 -134.5000
133 -135.0000
134 -134.0000
135 -134.5000
136 -134.0000
137 -135.0000
138 -135.0000
139 -135.0000
140 -131.0000
141 -135.0000
142 -135.0000
143 -136.5000
144 -131.5000
145 -135.5000
146 -131.5000
147 -134.0000
148 -121.5000
149 -131.5000
150 -132.5000
151 -133.0000
152 -129.5000
153 -131.5000
154 -130.5000
155 -129.5000
156 -125.0000
157 -123.5000
158 -126.0000
159 -123.0000
160 -116.0000
161 -109.5000
162 -121.5000
163 -126.0000
164 -128.0000
165 -128.5000
166 -129.5000
167 -127.5000
168 -128.0000
169 -122.0000
170 -128.5000
171 -125.0000
172 -129.5000
173 -126.0000
174 -127.0000
175 -116.5000
176 -123.0000
177 -123.0000
178 -126.5000
179 -126.5000
180 -127.0000
181 -129.5000
182 -129.0000
183 -129.5000
184 -128.5000
185 -128.5000
186 -127.5000
187 -126.0000
188 -115.0000
189 -126.5000
190 -128.0000
191 -129.5000
192 -128.0000
193 -131.0000
194 -126.0000
195 -126.0000
196 -127.0000
197 -127.0000
198 -123.5000
199 -125.0000
200 -123.0000
201 -125.5000
202 -126.0000
203 -123.5000
204 -122.5000
205 -121.5000
206 -123.5000
207 -123.0000
208 -123.0000
209 -120.0000
210 -116.0000
211 -107.0000
212 -119.0000
213 -121.5000
214 -122.0000
215 -122.5000
216 -121.5000
217 -124.0000
218 -122.5000
219 -118.0000
220 -123.5000
221 -118.5000
222 -122.0000
223 -121.5000
224 -121.5000
225 -122.0000
226 -123.5000
227 -124.5000
228 -120.5000
229 -123.0000
230 -122.5000
231 -122.0000
232 -120.5000
233 -120.0000
234 -123.5000
235 -123.0000
236 -125.5000
237 -122.0000
238 -118.0000
239 -124.0000
240 -124.0000
241 -124.0000
242 -122.5000
243 -125.5000
244 -117.0000
245 -125.0000
246 -124.0000
247 -124.5000
248 -125.5000
249 -125.5000
250 -125.0000
251 -121.5000
252 -114.5000
253 -114.0000
254 -121.5000
255 -125.0000
and the graph of that data is attached below.
There is a nasty looking peak between tone 45 - 47, so lets take a closer look. Examining the above raw data, we can see that peak is virtually tone 45 - 46. Performing the calculation --
fmax = ((46 x 4.3125) + 2.15625) kHz = 200 kHz
fmin = ((45 x 4.3125) + 2.15625) kHz = 196 kHz
The midpoint of those two frequencies is thus 198 kHz . . . and I don't need any look-up table to tell me that it is BBC Radio 4, broadcasting on long wave, from the Droitwich transmitting station (http://en.wikipedia.org/wiki/Droitwich_transmitting_station). ;D
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I can see it now as clear as a whistle with the QLN graph and then using the calculation formula.
I have to give BC the golden thumbs up it feels great to still be learning new stuff when your slightly over that middle aged bracket :-X
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Right BC you also have a peak at tone 160 and with the formula = 692.15 KHZ and using the link that would show up as Radio 5 Live as the source of RFI am I on the right track ?
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Right BC you also have a peak at tone 160 and with the formula = 692.15 KHZ and using the link that would show up as Radio 5 Live as the source of RFI am I on the right track ?
You most certainly are! ;D
A quick look at the raw data shows the peak to be approximately midway between tones 160 & 161.
Plugging tone "160.5" into the formula gives a frequency of ~694 kHz.
Using the UK Medium Wave Transmitters (http://www.mediumwaveradio.com/uk.php) web page and selecting the frequency of 693 kHz clearly shows the culprit -- the BBC Radio 5 Live transmitter at Postwick (http://en.wikipedia.org/wiki/Postwick), Norfolk. I say clearly, because anyone who has checked my profile (http://forum.kitz.co.uk/index.php?action=profile;u=3667) will know that The Cattery is located at Bury St Edmunds (http://en.wikipedia.org/wiki/Bury_St_Edmunds), Suffolk.
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www.ofcom.org.uk/static/archive/ra/publication/ra_info/ra365.htm
covers the total frequency allocations 9kHz -105GHz.
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Many thanks for that link, JGO. I now have it book-marked. :)
So for the bothersome "hump" of interference, at approximately 7.1 - 7.5 MHz, that NS has observed the above list shows --
7 100-7 300 kHz BBC broadcasting services operate within the bands 7 105-7 295 kHz,
BROADCASTING the channel spacing is 5 kHz and channel bandwidth is 10 kHz.
All services are transmitted via Rampisham, Skelton and Woofferton.
7 300-7 350 kHz BBC broadcasting services operate on 7 320 kHz and 7 325 kHz in
BROADCASTING this band via Rampisham, Skelton and Woofferton.
S5.134, S5.135, S5.143
7 350-8 100 kHz Government use.
FIXED NATS data links with Sumburgh
Land Mobile
S5.144
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Many thanks for that link, JGO. I now have it book-marked. :)
So for the bothersome "hump" of interference, at approximately 7.1 - 7.5 MHz, that NS has observed the above list shows --
7 100-7 300 kHz BBC broadcasting services operate within the bands 7 105-7 295 kHz,
BROADCASTING the channel spacing is 5 kHz and channel bandwidth is 10 kHz.
All services are transmitted via Rampisham, Skelton and Woofferton.
7 300-7 350 kHz BBC broadcasting services operate on 7 320 kHz and 7 325 kHz in
BROADCASTING this band via Rampisham, Skelton and Woofferton.
S5.134, S5.135, S5.143
7 350-8 100 kHz Government use.
FIXED NATS data links with Sumburgh
Land Mobile
S5.144
Many thanks for looking into this spike at 7280KHZ and yes that Station transmission was UK english and the Voice came through strong using wide band FM. but that station is silent to-night :-\
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Neutron Star - Just noticed Wideband FM on 7280 kHz ???????
Wideband FM at that frequency is totalty illegal, 75kHz deviation doesn't fit in 5kHz AM channels. So either a pirate OR maybe something very wrong with a FM radio radiating at IF (well more or less. IF is normally 10,700 kHz so 7280 is in the ball park.)
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Neutron Star - Just noticed Wideband FM on 7280 kHz ???????
Wideband FM at that frequency is totalty illegal, 75kHz deviation doesn't fit in 5kHz AM channels. So either a pirate OR maybe something very wrong with a FM radio radiating at IF (well more or less. IF is normally 10,700 kHz so 7280 is in the ball park.)
There are several Radio Stations that are being picked up from tones 1675 to 1760 and all are being broadcast outside the UK and I have enclosed a snapshot of the tones in question.
On one of those stations I was not able to get a lock on hear the Voice went through AM and then NAM it was when Wide FM was selected I could clearly hear the audible voice from that station so you can make your own conclusions why this was the case on this particular Radio Station.
Edit I have uploaded the same Bitloading Graph but this time the sun has set and the radio propagation is in full swing.
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NAM ? Never heard of it - should it be NFM or NBFM ?
If you have genuine FM with the standard 75 kHz deviation then it occupies on average 225 kHz all by itself. No need for anything else to punch a hole in the tones ! If that is the case something weird going on, but you are on the spot.
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NAM ? Never heard of it - should it be NFM or NBFM ?
If you have genuine FM with the standard 75 kHz deviation then it occupies on average 225 kHz all by itself. No need for anything else to punch a hole in the tones ! If that is the case something weird going on, but you are on the spot.
You have never heard of NAM you live and learn. :) NAM = Narrow AM
Frequency Coverage: 531kHz - 1320Mhz continuous
Modes of FM, WFM, AM, NAM, USB, LSB, CW
Step sizes: 50Hz, 100Hz, 1kHz, 5kHz, 6.25kHz, 8.33khz, 9kHz, 10kHz, 12.5kHz, 15kHz, 20kHz, 25kHz, 30kHz, 30kHz, 100kHz, 125kHz
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So NAM is your receiver convolving bandwidth and modulation mode - very explicit !