US military supplier orders Advantech SCPC modems for A-SATTM VSAT

A major U.S. military supplier placed an order with Advantech AMT Corp. USA for $1.7 million worth of the Company's DISA Certified MIL-STD-188-165A, AMT73L SCPC Modem, which will be used to deliver secure satellite communications systems over the Discovery A-SATTM VSAT system.

The AMT73L is designed to fulfill two-way satellite communication requirements in Defence Satellite Communications Systems (DSCS) and Wideband Global SATCOM System (WGS).

The installed base of the AMT73L DISA Certified Modems can be overlaid by the Discovery A-SATTM VSAT platform. In addition, the DVB-RCS waveform can be incorporated into Discovery through the integration of SCPC networks.

The Advantech Wireless family of high throughput modems boast of high reliability and flexibility. The AMT75 platform can handle ASI HD Video, Telco, and IP interfaces while the FLS-100 allows these modems to achieve up to 155Mbps throughput through IPE.

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Computing for the maximum transmit cable length of a VSAT Internet system?

Note the BUC gain and power supply requirements. Note your minimum and maximum modem output levels.

Using the BUC gain work out the appropriate input level for saturation.

Calculate the modem levels for various BUC output levels and try to design a system that allows the BUC to saturate with the modem perhaps still 5 dB below its maximum output. Operating any equipment at its extreme limits is not recommended. That gives you the dB loss for the transmit IFL cable, review the cable spec at L band to find the length. If you will be operating a very small carrier, with the BUC at very low power, e.g. 0.1W then take this into account, or use a lower power BUC. You dont want to get into the situation where you can't reduce the power sufficiently, even with the modem ats it minimum output. A longer cable may provide useful L band attenuation while allowing the DC and 10 MHz reference through.

Using the power requirements of the BUC, e.g. 55W at 15 to 24V.What power can your modem put out without overheating etc. If marginal then use an external power supply with cooling fan etc.

For higher powers, like 55W, it helps to use the maximum voltage at the modem end, in this case 24V. This minimises the current (amps) and thus the voltage and DC power loss in the cable. Solid copper centre wire is mandatory. 50ohm cable may be helpful as it has a thicker centre wire, if the modem and BUC can match 50ohms. Copper coated steel centre wire must be avoided!. Be conservative. Ask if the DC current taken by the BUC is smooth. It may comprise spikes at the switch mode power supply frequency and may spike also when the modem transmits a burst. Work out the cable ohms and compare with the cable specification versus length. DC power is very demanding on the coax centre pins, centre socket springs and the sheath wire connection at the plugs. A smear of electronic grade silicone contact grease can help exclude oxygen and moisture from the metallic points of contact.

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Satellite Broadband for the US via Dish Network

With the recent improvements in the US satellite industry, the country now has the technological capacity to support a nationwide satellite broadband project. The advancements in the satellite sector now enables operators to use higher-frequency bands.

Dish Network to deliver satellite broadband nationwide

Dish Network, in particular, is planning to roll-out internet by satellite with the help of EchoStar Corp's spacecraft, the EchoStar 17 satellite. The spacecraft itself has been delivering increased bandwidth capacity and can provide up to 15 megabits in download speeds. However, expect the broadband-Internet service to offer lower speeds, at around 5 megabits, in order to increase capacity for more customers.

The time frame for the project's implementation would be around September and October. Dish Network is targeting consumers in rural regions who are unable to access the Internet with the help of terrestrial infrastructure like cable broadband. 

The company has been offering broadband-Internet service via satellite in partnership with ViaSat, although the offers was limited to specific regions of the US. The latest project, however, will see Dish Network offer packages and bundles which would include video services.

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