Thanks for your reports from the past weekend. Because of travel earlier this week, I'm very much behind in responding, but I'll try to get that done before the end of the weekend.
We had good results last weekend, as illustrated by these images of the National Christmas Tree all received on 17860 kHz by listeners from Estonia to California.
Even though we are in the midst of the holiday season, our experiments continue.
Our MFSK64 mode centered on 1500 Hz has data from 1000 to 2000 Hz, with a second audio harmonic from 2000 to 4000 Hz.
Technically, there is no overlap, but there is also no "guard band" between the fundamental and the second harmonic. This can cause interference, especially with less selective, lower cost receivers.
To determine if a guard band would be helpful, we will first transmit an MFSK64 image on our usual center audio frequency of 1500 Hz.
Then we will move the center audio frequency up to 1700 Hz. The fundamental will be 1200 to 2200 Hz. The second harmonic from 2400 to 4400 Hz. The guard band will therefore be 200 Hz wide, between 2200 and 2400 Hz.
Here is the lineup for VOA Radiogram, program 38, 21-22 December 2013:
1:33 MFSK16: Program preview (2:58)
5:40 MFSK32: Introduction to experiment (1:21)
7:36 MFSK64/1500 Hz: Image of Christmas tree (2:05)
10:17 MFSK64/1700 Hz: Same image of Christmas tree (2:05)
12:22 MFSK64/1700 Hz: Collapse of universe (3:39)
16:15 MFSK64/1700 Hz/Flmsg*: Electronic waste, with image (3:26)
19:41 MFSK64/1700 Hz: Converting algae to oil, with image (4:19)
24:41 MFSK64/1500 Hz: Same image (1:46)
26:38 MFSK32/1500 Hz: Closing announcements (:35)
*Use Flmsg with Fldigi. *To make Flmsg work with Fldigi (both can be downloaded from w1hkj.com), in Fldigi: Configure > Misc > NBEMS -- Under Reception of flmsg files, check both boxes, and under that indicate where your Flmsg.exe file is located.
Please send reception reports to radiogram@voanews.com
VOA Radiogram transmission schedule
(all days and times UTC)
Sat 1600-1630 17860 kHz
Sun 0230-0300 5745 kHz
Sun 1300-1330 6095 kHz
Sun 1930-2000 15670 kHz
All via the Edward R. Murrow transmitting station in North Carolina.
VOA Radiogram schedule change 28 December
On 28 December 2013, VOA Radiogram will add a new transmission Saturday at 0930-1000 UTC on 5745 kHz.
To keep the VOA Radiogram schedule to its modest two hours per week, the transmission on Sunday at 1300-1330 UTC on 6095 kHz will be discontinued after the broadcast on 22 December 2013.
I hope to hear from you this weekend.
Kim
Kim Andrew Elliott
Producer and Presenter
VOA Radiogram
voaradiogram.net