ANDE stands for Atmospheric Neutral Drag Experiment and is a 19" sphere with optical corner reflectors for precise orbit determination. The Naval Academy is building the Telemetry and command/communications payload for ANDE similar to what it is flying on the PCsat mission as both a means to transmit spacecraft Telemetry to the ground and to augment the interest of students worldwide by letting them capture telemetry and communicate via the satellite.
It has no solar power, so when the 7000 Watt Hours of batteries (112 Lithiums) die then it too will die (+- 700 days)ANDE TELEMETRY/COMMAND/COMMUNICATIONS PROJECT

Students: Midn 1/C Patterson
Faculty and Staff: Bob Bruninga (WB4APR)

MISSION: The Comm payload for ANDE is to provide a flight proven Telemetry
and command system for ANDE and if extra power is avaiabole, a secondary
mission to augment the constllation of other similar amateur satellites
(PCsat, ISS and Sapphire) serving as worldwide position/status reporting
and message communications satellites for remote travelers using only Handheld
or Mobile radios with Omni-directional whip antennas. It uses the APRS
(Automatic Position Reporting System) protocols to permit hundreds of users
per pass to access the satellite. This constellation of satellites, will
augment the existing worldwide terrestrial Amateur Radio APRS tracking
system by providing links from the 90% of the earths surface not covered by
the terrestrial network. It will be licensed in the Amateur Satellite Service.

BACKGROUND: Today, 95% of the US amateur population is covered by the
terrestrial APRS network, BUT only 30% of the surface area of the USA is,
or will probably ever be, covered. Similarly in just the last year we have
seen explosive growth in the European theater as well. But, distant travelers,
boats at sea, and stations in the rest of the world are presently unable to
use the APRS system as a travelers safety reporting system when on distant
trips. Until the activation of PCsat, the APRS network only covered less than
5% of the world's surface. The APRS payload on these satellites will not only
make such reporting possible throughout the world, but by having more than
one satellite, will give the program reliability and continuity and
connectivity more often than a single satellite can provide.

FREQUENCY CONSIDERATIONS: Two meters is the ideal band for this mission due to
the requirement for user access using only a handheld radio. Two meters
offers a 9 dB link advantage over UHF. To take advantage of this advantage,
the HANDHELD uplinks will be on two meters and the downlink will also be on
2 meters. This assures the best reception by mobiles and handhelds both with
only omnidirectional antennas. Higher power mobiles who have 10 dB greater
uplink power may use UHF but only if there is sufficient power budget on
ANDE to support the two receivers. Multiple receivers splits the
contention on the uplink channels and doubles overall throughput.

DOWNLINK: The downlink is the same as PCsat on 145.825

UPLINKS: The uplink is the same as PCsat on 145.825 for Handhelds
and 435.250 for high power 9600 baud mobiles.

INTERNET LINKED GROUND STATIONS: APRS is unique in the way it combines all
packets heard everywhere in the world into a single common internet feed
channel. THus the infrastructure for distributing APRS traffic no
matter where its source into all other stations already exists. By adding
ANDE on the same frequencies as PCsat, the existing worldwide internet
linked groundstations will also link to Starshien with no additional effort.

WB4APR, Bob

Official ANDE Home Page

ANDE POWER SYSTEM ENERGY BUDGET 21 Oct 2002
---------------------------------------------------------------------------
Bob Bruninga

BATTERY SYSTEM: Lithium-primary
Battery Mass: 11.2 Kg
Battery Construction: 112 Cells Tadiran TL-5930
Each cell is 93 g and 33 x 62 mm
Battery volume: 7562 cu cm
Battery configuration: 28 4-cell strings in parallel
Battery volts: 12 volts (14.4v no load)
Battery safety: Every 4-cell string fuzed individually
Battery capacity: 532 AHrs (7448 WHrs at 14 volts)

ANDE Telemetry/Command system:
Subsystem current D/C standby D/C in-use USAGE AVG CURRENT
--------- ------- ----------- ---------- ----- -----------
Receiver 30 mA 10% 100% 10% 6 mA
TNC 15 mA 10% 100% 10% 3 mA
XMTR 600 mA 0% 20% 10% 12 mA
LASERS 250 mA 0% 100% 0.3% 1 mA
Timer Ckts 1 mA 100% 100% 100% 1 mA
---------------------------------------------------------------
Total 23 mA
Overall conversion efficiencies of 75% result in: 32 mA

Battery life: 532 AHrs/32 mA = 16,600 hours = Almost 700 days.

The total life is drastically dependent on the usage duty cycle.
The above figures assumed a worse case scenario. Typical and
target values could allow for more than 1.5 year life and still
support nominal communications via the PCsat-style operations...

The figures above assume the comm payload operates on a power-saver
circuit which only wakes up for 2s out of every 20 seconds (10%).
Once a valid packet is detected, then the receiver/TNC remain on
for the next 60 seconds to support any telemetry and user access.
Typical usage will be over USA, Europe, Australia and Japan.
There, using the carrier-sense-multiple access half duplex channel,
transmit duty cycles will be optimum at about 20% channel loading.