Category Archives: Digital

DSLWP amateur radio satellites launched to Lunar orbit

DSLWP is a lunar for­ma­tion fly­ing mis­sion led by Harbin Insti­tute of Tech­nol­o­gy for low fre­quen­cy radio astron­o­my, ama­teur radio and edu­ca­tion. It con­sists of a pair of 47 kg microsatel­lites launched from the Xichang Space Cen­ter into a lunar trans­fer orbit at 21:28 GMT on Sun­day, May 20, 2018 and they will enter a 300…


China’s twin-launch Chang’e 4 mis­sion to the far side of the moon will place a pair of microsatel­lites in lunar orbit “to test low-fre­quen­cy radio astron­o­my and space-based inter­fer­om­e­try.” The two satel­lites, DSLWP-A1 and DSLWP-A2 (DSLWP = Dis­cov­er­ing the Sky at Longest Wave­lengths Pathfind­er) are expect­ed to launch in June. They will car­ry Ama­teur Radio and edu­ca­tion­al pay­loads, but not a transpon­der.

Equipped with low-fre­quen­cy anten­nas and receivers, the astron­o­my objec­tives of the two space­craft will be to observe the sky at the low­er end of the elec­tro­mag­net­ic spec­trum — 1 MHz to 30 MHz — with the aim of learn­ing about ener­getic phe­nom­e­na from celes­tial sources. They will use the moon to shield them from radio emis­sions from Earth.


Devel­oped by stu­dents at Harbin Insti­tute of Tech­nol­o­gy (BY2HIT), the Ama­teur Radio pay­load onboard DSLWP-A1 will pro­vide a telecom­mand uplink and telemetry/digital image down­link. The open telecom­mand pro­to­col is designed to allow ama­teurs to send com­mands to take and down­load images. DSLWP-A1 down­links are 435.425 MHz and 436.425 MHz; DSLWP-A2 down­links are 435.400 MHz and 436.400 MHz, and they will use 250500 bps GMSK using 10K0F1DCN or 10K0F1DEN (10 kHz wide FM sin­gle-chan­nel data) with con­cate­nat­ed codes or JT4G. JT4 uses four-tone FSK, with a key­ing rate of 4.375 baud; the JT4G sub-mode uses 315 Hz tone spac­ing and 1260 Hz total band­width.

The microsatel­lites rep­re­sent the first phase of the Chang’e 4 mis­sion. The satel­lites will pig­gy­back on the Chang’e 4 relay pack­age and will deploy into 200 × 9,000 kilo­me­ter lunar orbits. The mis­sion involves plac­ing a relay satel­lite in a halo orbit to facil­i­tate com­mu­ni­ca­tion with the Chang’e 4 lan­der and rover, which will be sent to the far side of the moon in Decem­ber. Because the moon’s far side nev­er faces Earth, the satel­lite is need­ed to serve as an Earth-moon relay. The Chang’e 4 mis­sion will be the first-ever attempt at a soft-land­ing on the far side of the moon.

From  ARRL

Lunar Amateur Radio Satellites DSLWP-A1/A2

Mingchuan Wei BG2BHC reports DSLWP is a lunar for­ma­tion fly­ing mis­sion for low fre­quen­cy radio astron­o­my, ama­teur radio and edu­ca­tion, con­sists of 2 microsatel­lites. Devel­oped by stu­dents at the Harbin Insti­tute of Tech­nol­o­gy the ama­teur radio pay­load onboard DSLWP-A1 will pro­vide telecom­mand uplink and teleme­try / dig­i­tal image down­link.


As a trained severe storm spot­ter (not chas­er) I need to make accu­rate posi­tion reports when I make severe storm reports des­tined for the Nation­al Weath­er Ser­vice and the coun­ty Emer­gency Man­ag­er (usu­al­ly at the 9−1−1 call cen­ter). By train­ing we report the dis­tance and direc­tion from the near­est major inter­sec­tion. This is where prob­lems can enter the equa­tion.

These reports are via a ham radio net­work. The assump­tion is that we clear­ly pro­nounce the names of the roads we are near for exam­ple. And that we know the dif­fer­ence between being on a street, road, avenue, etc.. That, of course, is as long as we can see the road signs in the pour­ing rain, dark­ness and winds that we dri­ve through. Next con­sid­er­a­tion is the guess at the dis­tance and direc­tion from the near­est inter­sec­tion. How accu­rate is that in a rain storm? Then comes the issue of map loca­tion. Does the map that the per­son you are report­ing your loca­tion to have the lev­el of map detailed need­ed to locate the roads you are report­ing? More impor­tant­ly, does every­one in the com­mu­ni­ca­tions net­work have the same lev­el of map details?

Intro­duc­ing a nice solu­tion — APRS (Auto­mat­ic Pack­et Report­ing Sys­tem) Con­nect­ed to a GPS sen­sor on one side and a ham radio on the oth­er side a TNC (ter­mi­nal node con­troller) trans­mits any ham radio oper­a­tor’s EXACT coor­di­nates (with­in about 50 feet) to (effec­tive­ly) a Google map on the inter­net. Any­one any­where that has an inter­net con­nec­tion (and many with just a ham radio sta­tion with­out an inter­net con­nec­tion) can dis­play the exact loca­tion, alti­tude and direc­tion of trav­el (at least) almost instant­ly. Since Google maps are zoomable to var­i­ous lev­els the desired lev­el of detail is but a click or two away.

Trav­el path is also be auto­mat­i­cal­ly plot­ted. A nice bright blue line con­nects the red dots that rep­re­sent the points of trans­mis­sion of the APRS device. A quite nice fea­ture of an APRS Google map (see an exam­ple at http://APRS.FI) hap­pens when your mouse point­er hov­ers over one of the red trans­mis­sion points. A sep­a­rate red line pops up that indi­cates what ham radio sta­tion heard the trans­mis­sion. With that infor­ma­tion you can trace the route of the data from the GPS device into the inter­net.

Anoth­er nice fea­ture of report­ing data via dig­i­tal data trans­mis­sions to the Nation­al Weath­er Ser­vice is that many peo­ple that have access to the inter­net Google map can view the infor­ma­tion at one time.

As a side note, Face­book — the social net­work — now has an APRS appli­ca­tion that makes these APRS maps of all of your friends avail­able at the click of one but­ton from your Face­book page! One pos­si­ble appli­ca­tion is to have the Nation­al Weath­er Ser­vice become friends for all severe storm spot­ters. Then they would have this data avail­able at the click of one but­ton!

Source by Jon Kres­ki

Category: Digital, Misc, Software


Prob­a­bly just about every ham has heard of var­i­ous “nets” that oper­ate with RF only. Most cities have a local club or local repeater net. Net being a short form of the more for­mal net­work. Most A.R.E.S. groups, usu­al­ly orga­nized by coun­ty, have a week­ly net. A.R.E.S. of course stands for Ama­teur Radio Emer­gency Ser­vices group. On the HF side of things there are wide rang­ing nets such as the Coun­ty Hunters net. There are RV nets designed to com­mu­ni­cate with and amongst recre­ation­al vehi­cle own­ers. And of course there are mar­itime nets designed to be of assis­tance to ships of all sizes and types at sea.

In the past 5 — 10 years hams have begun to inter­face their radios with com­put­ers to form new types of net­works. These can be con­fus­ing and for­eign. In fact, some ham radio per­a­tors believe that if you oper­ate via these types of net­works that it is not “real” ham radio. First I will explain a few of these types of net­works and then I will give my ever so hum­ble opin­ion.

IRLP — this net­work is the Inter­net Radio Link­ing Project. The objec­tive is to use the best fea­tures of these two types of com­mu­ni­ca­tion pipes to pro­duce a more pow­er­ful com­mu­ni­ca­tion pipeline. The net­work in sim­ple form allows a ham’s radio to be con­nect­ed to one inter­net con­nect­ed com­put­er. At the oth­er end of the inter­net con­nec­tion (and this is a many to many con­nec­tion) anoth­er com­put­er receives the inter­net data sent by the first com­put­er and relays it to anoth­er ham radio which then trans­mits the com­mu­ni­ca­tions back over ham radio fre­quen­cies. Here’s the advan­tage. A small hand held radio with­in com­mu­ni­ca­tion dis­tance of an IRLP linked ham radio now can com­mu­ni­cate with many hams all around the world with FM and VOIP qual­i­ty! How much is this world­wide net­work? FREE!


EchoLink — The basic part of this net­work is a clone of the IRLP net­work. This net­work takes com­mu­ni­ca­tions one step fur­ther. With EchoLink you add the abil­i­ty to com­mu­ni­cate from your com­put­er with a micro­phone and speak­ers first. Then the audio goes through the inter­net pipe and out through a dis­tant con­nect­ed ham radio. This net­work is also FREE!

d‑Star — This net­works takes the EchoLink net­work even one step fur­ther. As long as your radio is con­nect­ed to your com­put­er — this net­work adds the capa­bil­i­ty to trans­mit data files. Here’s the neat part. No inter­net con­nec­tion or the inter­net is down? No prob­lem — d‑Star can han­dle the data trans­fer all via radio! And this net­work is also FREE!

While the net­works are FREE, equip­ment required to access the net­work (radio, com­put­er, etc.) does have to be acquired. Also, there may be a very small fee to have your radio license con­firmed. And, you must be a ham radio oper­a­tor to access these net­works.

Now for my opin­ion — are these net­works “real” radio? Not accord­ing to those stuck in the mud folks that real­ly don’t see these net­works as the nat­ur­al evo­lu­tion of con­verg­ing tech­nolo­gies. To them it’s like cheat­ing if you use any­thing oth­er than radio waves to com­mu­ni­cate. I under­stand that the accom­plish­ment for long dis­tance com­mu­ni­ca­tions is not the same. But these net­works ARE real ham radio. They are the future. They vast­ly improve com­mu­ni­ca­tions and the abil­i­ty to com­mu­ni­cate is one of the major objec­tives of ham radio.

Are there too many radio net­works? NO! Each one is a new step for­ward. Just like dig­i­tal com­mu­ni­ca­tions modes they each have a pur­pose and have built fol­low­ers and equip­ment infas­truc­ture. There is room for plen­ty more!


Source by Jon Kres­ki

Category: Digital

Solar-Terrestrial Data

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