Jag Venugopal's Blog

February 12, 2010

India’s Space Ambitions

Filed under: India — Jag @ 7:54 pm


There has been a lot of recent talk about India’s space ambitions, whether it be launching an astronaut into space, or landing a man on the moon. Ambitions are great, but it is also time for some realistic thinking.

 The one consistently successful rocket booster that India possesses is the PSLV. This rocket is designed to put a 1600 kg payload into a sun synchronous orbit, or a 1000 kg payload into GTO. The PSLV has notched up a few interesting stunts, such as orbiting 10 satellites all at once. In addition, ISRO has provided launch services on the PSLV to other countries, thus earning some money.

 India has another, more powerful rocket in the GSLV, that can place 2000 kg into GTO. It is on this booster and its progeny that most of India’s space hopes and promises rest. The story of the GSLV though, is still being written. At this point, it is not even a wholly Indian launcher.

 The GSLV’s third stage is a so-called “cryogenic stage”, which burns liquid hydrogen and oxygen. India has been trying to create this engine since at least the late ’80s. The first engine is scheduled to fly in 2010 after multiple delays. Until now, India has had to make do with ready-to-fly engines sourced from Russia. Before the GSLV can achieve true operational status, the Indian engine has to fly multiple times and prove that the GSLV is a consistent and safe launcher. The record on this score is not particularly reassuring at this point: One outright failure, and two partial failures where the satellites were injected into suboptimal orbits (including the latest GSLV flight). Indian journalists are only too happy to swallow ISRO’s press releases about the country joining this “exclusive space club” or that, rather than questioning why after so many years, India still hasn’t mastered the technology. Also accepted without question is ISRO’s constant changing of timetables. The GSLV was supposed to fly sometime in 2007-2008. At best it will fly in 2010 (and if there is a failure, a further delay of 2-3 years).

 The GSLV-III, a medium-lift launcher, capable of transferring about 4000 kg to GTO was supposed to be launched in 2009. The date moved to 2010, and now 2011 is being thrown around. How they can promise a 2011 launch is beyond me, considering that they haven’t flight-tested the 3rd stage engine on its predecessor (the GSLV-III needs a significantly up-rated version of the engine that India’s been struggling to build for the GSLV).

 None of this is meant to denigrate India’s achievements in space, be they in communications, earth-sensing, or weather satellites. However when it comes to launch vehicles, India’s journalists should develop some basic knowledge and call ISRO on its inability to successfully develop the GSLV, even though almost a decade has passed since its first “semi-successful flight”. The mandarins of India’s space program must give a clearer roadmap of how India intends to achieve its ambitions, rather than spouting fancy targets and goals (manned missions, the moon, Mars, …) at random every few days.


Keeping In Touch With Walkie-Talkies

Filed under: Digital Living — Jag @ 4:46 pm

Families are well served by a communications device when they are dispersed over a wide area such as a large mall, amusement park, golf course, or just the great outdoors. Such devices help family members take some time off to pursue their individual interests, while still staying in touch. Examples of such devices are the cell-phone, and the walkie-talkie.

Cell phones are ubiquitous, almost everyone has them, battery life is good, and overall, they are inexpensive. However, they have their own drawbacks:

  • They are expensive to replace if damaged or lost
  • They require proximity to a cell tower to function
  • They still cost money

 Over the last decade, inexpensive, yet efficient walkie talkies have emerged on the marketplace that may serve a family’s communication needs, while mitigating some of the drawbacks of cell phones. Such gadgets are:

  • Inexpensive (they typically run less than $100 per pair)
  • Do not require cellular infrastructure to operate (they work fine in the wilderness)
  • They don’t cost anything to operate (other than the cost of batteries)

Most walkie-talkies sold at electronic retailers come in pairs, in a bubble-pack. They operate on the FRS and GMRS frequency bands. The former is license-free, and the latter needs a license from the FCC. The license costs in the neighborhood of $85, and needs to be renewed every five years (though a perusal of the FCC licensing database for GMRS will reveal that unlicensed use is the norm, and the licensing requirements are almost never enforced. As proof, there are less than 2000 active GMRS licensees for the state of Massachusetts).

 By law, transmissions on the 15 GMRS and 7 FRS frequencies are expected to be clear (i.e. no scrambling or encryption). With 22 channels and a number of users, congestion and interference is very likely in crowded places (where they are most likely to be used). Manufacturers tout “privacy codes”, which can be misunderstood as a feature that makes your conversations private. In fact, what they do is to keep other conversations on the same channel (but without the same privacy code) from being received by you. So, its more a nuisance-avoidance code rather than a privacy code.

 On the positive side, there are a number of GMRS/FRS walkie-talkie manufacturers, and most devices are fully interoperable with each other. Emergency hand-cranked radios also incorporate these walkie-talkies, thus allowing someone stuck or lost to try reaching rescuers without the need for fresh batteries.

 Another kind of walkie-talkie that has been on the market for the last three years is a new twist on the old 900 mHz cordless phone. This proprietary technology (called eXRS) works on the license-free 900 mHz band. A major difference between this technology and FRS/GMRS (other than the different frequencies) is that these radios change their frequencies every 400 milliseconds from a pool of about 50 , in a pseudo-random sequence that can be set by the user.

 eXRS devices solve the privacy problem rather nicely. Unless a potential eavesdropper has fairly sophisticated scanning equipment, it will be difficult to tap into a conversation. This makes it sufficiently safe and private for the family in recreation mode. There is no one that can listen in on private conversations, and no one that can interject their words into a private conversation — both features making the devices much safer for kids.

 Other advantages of eXRS are that no licensing is required, and the technology is scalable to many more concurrent users (the manufacturer claims that 100,000 users can be using the device in a given area without congestion. Even assuming that they have exaggerated by a factor of 10, there is plenty of scalability built in).

 There are two disadvantages of eXRS devices: They come from a single manufacturer, and are not an industry standard. This means that the rapid pace of innovation in the GMRS marketplace may outpace the lone eXRS manufacturer’s resources. For example, the currently available eXRS radios are not as rugged as the most rugged FRS/GMRS sets available. There are no hand-cranked versions available either. Secondly, they don’t help much as an emergency radio — the privacy features get in the way. The same frequency hopping that affords privacy, also prevents rescuers from communicating with someone lost, using this technology.

 With these caveats in place, I would make the following recommendations for a family that wants to stay in touch in the outdoors:

  • Purchase and use a pair of eXRS radios for general communication among dispersed members
  • Those going camping in out-of-the-way places might also want a hand-cranked radio with GMRS to use in emergencies

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