Special report during IARU contest 9 th and 10 th July 2005

Equipment in use: - Kenwood TS940. Visual spectrum monitoring program: -   Spectran V2 Build 213 by I2OHD and IK2CZL.   Propagation program Hamcap v 1.2.   Direction bearing and distance by DX Atlas version 2.25 both from VE3NE

Observation location: - Grid NK98mm Lat. 18:52:72 North. Long. 99.01 East.

Antenna systems 2 element 3 band cubical quad at 35 meters. 40 metre antenna, dipole at 20 meters, wire axis East West. Solar condition 9 July at 1505 GMT. SF110, A = 5, K = 3, NOAA Sunspot 111.

Monitoring Commences: -

Sat 9 July 2005 1404 GMT 10 Meters band : -. Radar Pulses peaking on 28.764 MHz appear to be notched out 30Khz around 28.500Mhz. Transmissions bearing 105 degrees from Chiang Mai, first land fall / land sea coastal area along the line 105 degrees is 3W3 16:35N 107:39E grid OK36to, range 942 Klm. Attached audio and spectrum files. Comments: - there appears to be an attempt to prevent interference to the DX calling frequencies. Also the audio seems to be tailored with a distinct reduction below 800 cycles within the audio spectrum.

Sat 9 July 2005 1414 GMT 28.764 MHz . Radar pulsing with intermittent like fat frying noises, this is due to abrupt changes in repetition audio phasing of several milliseconds. Bearing 360/ 0 degrees running along the line 0 North at 897 Klm is BY8S at 27N 99:11E grid NL97oa. Further North is BY8A at 1521 Klm 32.38N 99 E grid NM92. The best possibility according to propagation predictions is JT1 at 3,172 Klm 47:29N 99:09E grid NN97.

Sat 9 July 2005 1420 GMT 40 Meter band . No discernible radar interference at this time!!!, although a very low-level radar like signal is on 6.95 MHz with 3Khz modulation. The absence of daily 60 dB to 80 dB over nine, radar interference is remarkable, and a pleasure to hear clearly stations on 40 meters this time of night from JA, DU, and VR2's etc.

1715 GMT Frequency 7.045 MHz. 8x8 Havana gurgle loud. Aprox 10 kHz wide.

2300 GMT Frequency 7.067 MHz. RADAR over 40 kHz wide at “S” 50 dB. Dxing is not possible due to the above Radar QRM obliterating all signals. Location unknown.

0000 GMT. Band full of QRM, USB pirates, chit-chat, and a verity of data type transmissions. Band back to its normal daily mess.

Sunday 10 July 0300 GMT 20 meters band. : - Radar 14.067 MHz Bearing 195 degrees, audio flat response, mostly modulated with 100 cycle pulses but changes intermittently by adding extra 50 cycle pulse, sounds like fat frying. There is a distinct audio band between 750 to 900 cycles where some sort of activity cause the modulated to become disturb. There is a similarity with the same kind of radar signal on bearing 105 degreases. On this bearing (105) the signal is very strong but the modulation is weak.   On bearing 195 the signal is some 10 dB reduces but the modulation is much stronger.

Note: - Bearing 195 degrees first land fall along this line is the most northerly tip of Sumatra at 5:44N 95:25E grid NJ57rr. Distance 1521 Klm

At 0400 GMT both signal went into wide space audio modulation now covers the entire amateur band. Both signals are down to S9. This simultaneous occurrence to both stations on bearing 195 and 105 degrees indicates the possible existence of backscatter reception. However the bearing width is very sharp within 10 to 15 degrees of arc on each bearing, with a distinct peak within a few degrees.

Sunday 10 July 0420 GMT 20 meters : - Radar interference to 20 meters centred around 14.554 MHz. Bearing 140 degrees. In AM reception modes the S meter read 40 dB over nine. In SSB mode, very little audio can be heard but the S meter reads a steady S9, no DX can be heard threw the QRM

Sunday 10 July 04300 GMT 15 metres . Radar bearing 140 degrees peaks at around 21.127Mhz but covers most of the amateur band. The modulation undergoes several changes of patters from fat frying to a cycling sound. Spectrogram shows at times distinct missing pulse at 50 cycle intervals. Even pulse at 100 cycles remains constant.

Note: - bearing 140 degrees intersects the southern east Australia coast at 37:38.S 149.41.E grid QF42ui at 8,211 Klm. (Known site at Laverton SW Melbourne 143 degrees !!!!) Propagation is via F2F2 Mode. Calculations show with a conservative RMS power level of 10 Kilowatts the receive level at this QTH is predicted to have a signal to noise level of 53 dB at the lowest angle of arrival.

Sunday 10 July 10:16 GMT 10 meter band . : - Radar observed peaking on 28.769 MHz bearing 105 Degrees. It is notice at high audio spectrum resolutions that that deep pan frying sound is cause by instantaneous sub modulation of each 100-cycle carrier. This is not constant on each sub carrier across the audio spectrum, but varies around each carrier in a digital cluster burst formation. This can be seen in the attached spectrograph pictures. The effect is to render 10 meter DX useless.

Sunday 1030 GMT 15 Meters band. : -   Clear at this time of any broadband radar interference. However radar is noticed on spot frequency of 21.332 MHz. Nominal bearing is 160 degrees. The modulation has more of a steady tone, but the modulation pattern is completely different, being at odd audio frequencies. A kind of sub modulation like a low frequency hum can be heard but not visually detected. Audio modulation pattern follows as: - 200, 240, 270 320, 400 cycles etc across my receivers audio band pass

Note, along the line 160 degrees the fist land fall is the north West Coast of Australia at 22:19.N 113:45.E grid OG67uq distance 4854 Klm. The line of 160 degrees also intersects the southern West Coast of Australia at a point of 34:26S 119:11E.   Grid 095on at a distance of 6300 Klm. Approximately around the Albany area.

Sunday 1100 GMT 20 meters band. :-   No discernible radio interference or Havana gurgle found. DX bands open to Europe Southeast Asia such as 9V. 9M2, JA, BV, YF, very nice propagation

1105 GMT.   2 minute burst of radar across 40 meters centred on 6.530 MHz.

1110 GMT.   7.0985 Havana gurgle narrow modulation S9

Foot Note 1.

Radar reception at this QTH spoils HAM RADIO operation on all bands. It is normally so strong to obliterate all amateur signal during daylight hours of HF and 40 meters during darkness. The high repetition pulse rate is not readily audible in SSB mode, but clearly detectable in AM especially with the aid of spectrum monitoring software.

Foot Note 2.

4x4, 8x8, 16x16, and 32x32, so-called Havana gurgles have not generally been heard or not observed. Exceptions have been very intermittent burst, and apparently seem to be more of intentional jamming, than a technical transmission.

Foot Note 3.

Monitoring of RADAR signal is intensely irritating for long periods, inducing a painful and lasting headache.

End of monitoring report during the IARU contest July 2005-07-10

MS coordinator for Thailand,

Sheridon Street   --   HS0ZEE