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Wed, 26 May 2004
Now this is Wireless Fidelity
The Link: Casey's Mobile Broadcast Station. Im sure a few special events are in order -- I just need to find myself a camera man. On a personal note, I am traveling to a function in eastern washington this weekend (Tri Cities). I'm bringing my gear with me and I should have the entire cell site to myself. Fri, 21 May 2004
Streaming Commute to Hack Night
Which brings me to my point....I've always wanted to stream audio/video wirelessly from anywhere, but what the hell does one do with it? Maybe I need my own reality TV show? Mon, 17 May 2004
Fun with CDMA2000
First Impressions The Merlin C201, in PCMCIA form-factor, looks almost like an Orinoco Gold. And like most WiFi cards, it is cross-polarized with the system it connects to. Other Sprint cards make use of vertical antennas, I am not entirely sure why Novatel went with this lame design. It was the cheapest of the 4 cards featured -- a mere $199 dollars, usually brought down in price by carrier subsudy. I paid $150 with my business discount and 1 year of service contract. As expected, throughput is quite nice. I average about 100kbps up and down, without the aid of compression. It works just as well at 80mph as it does at 0mph...with a few exceptions. Moving from good coverage to bad coverage is one of them.... More Streaming Fun With the help of Matt Wilson, I decided to put 1xRTT to the test: Stream live video FROM the mobile device; at 60mph; during rush hour. Results of Dual ISDN (Actual: 90Kbps) While in motion, the stream would go maybe a minute or two before chopping. After a little chopping, it started right up again. After a little tweaking with the connection medium (TCP or UDP), I determined that if the coverage dropped bellow 3 bars, sending 90Kbps of payload just was not going to happen. We don't have much head room for error if the coverage heads south. I suspect this will only work well in fixed operations, or with a good antenna to ensure signal strength is optimum. Results of Single ISDN (Actual: ??Kbps) "Single ISDN" would likely be a 64Kbps circuit. While this gave us more head room than Dual ISDN, we'd occasionally have a bit of break up in poor coverage areas. Results of 28k to 56k (Actual: 20-34Kbps) We were able to keep a stream going for a considerably long time (>10 minutes), even with 2 bars of signal. It seems that no matter what happened, it still pounded through. Final Thoughts While more testing will likely ensue, 1xRTT definately has a very nice upload that does not compare to anything else available. It will stay that way until UMTS (WCDMA GSM) or CDMA2000 Ev-Dv makes its way into the world. Note that while Ev-Do brings us over 2Mbps of download, it does not help our upload much. So Verizon's impact will be minimal this summer. It also is very fun to note that 1xRTT has been available in every CDMA coverage area since Vision launch in the summer of 2002...which is just about everywhere. Wed, 05 May 2004
Hype Definition
Resolutions and Aspect Ratios Since NTSC is analog, various TVs will display different screen resolutions. NTSC overscan is actually 736x482, but your TV will likely crop the outer edges of this, depending on model year, technology, and quality. The aspect ratio is 4x3 or 1.33:1. This makes almost a square box, slightly rectangle. In broadcast NTSC, audio is typically FM stereo, with the option of lower quality, secondary audio carriers. Film is usually sported in two major formats, 1.85:1 or 2.35:1. Film does not have a particular resolution in pixels, but film grain generally limits this from being infinite. Current digital televisions (DTV's) use the aspect ratio of 16x9 or 1.78:1. The digital transmission actually has tons of different video modes, and is called ATSC. ATSC can contain mutiple video "streams", data payload, TV schedule information, and several different audio modes encoded in AC3. These audio modes can provide either surround sound (5.1-like experience), stereo, or mono. ATSC uses VSB for transmission. Originally, OFDM was to be used, but this was changed for some reason. OFDM would have given HDTV resistance to multipath, and actually make reception in most areas possible. The Europeans will be using OFDM. Instead, VSB cuts our broadcast tower range (compared to analog services) in half or perhaps by 2/3's, depending on the antenna technology employed. VSB comes in two flavors, "terrestrial rate" and "high rate". "terrestrial rate" is 19.36Mbps and uses 8 level VSB (8VSB). "high rate" transmits at 38.57Mbps using 16 levels (16VSB). Currently, no broadcast transmissions use the higher 16VSB rate.
While these resolutions and aspect ratios are quite impressive, our cool new digital televisions will still letterbox some movies shot in 2.35:1. But a lot of movies are shot in 1.85:1 -- thats close enough to 1.78:1 to where it is expanded to fill the entire screen (!) Digital Television vs. High Definition While Digital Television brings us a lot of different modes, some are considered "high definition" and others are just considered "digital television". 720p and 1080i are considered true, high definition. 480p and 480i are considered "digital television". 720p vs 1080i and your television While the mode 1920x1080i is my favorite mode, some claim (the inferior) mode 1280x720p is better. Either way, before you decide what side you are on, keep in mind that a vast majority of broadcasters have adopted 1080i. Make sure your TV supports at least 1080i. Your TV will still be able to view "720p", even if it has to scale it up to fit your television's 1080i native resolution. Some will do 720p and 1080i. Some televisions just display 720p. I would stay away from the 720p-only televisions, even at their discounted price. You are only robbing yourself of higher modes. Also be careful of some displays, including some plasmas and LCD's. Keep on eye on their native resolutions -- some will not display anywhere near the 720p and 1080i sizes and downscale. HDTV Content Delivery Content delivery is still a sticky issue, as service providers scramble for bandwidth. Even with better compression systems available (mpeg4) HDTV channels require the bandwidth of 5-10 regular television channels. Over the Air A lot of stations have brought digital 8VSB stations on the air already. Some operate at high power, others do not. Most of it is a digital version of the 640x480 interlaced content we see on TV today...with the exception of some prime time TV shows and movies. Sick of those black bars on your analog TV -- wait until you see most of your content with black pilars on the side! Some channels are providing "HDTV" content in 703x480, in "widescreen" or 16x9 ratio. To receive over the air broadcasts, you must purchase a special HD decoder box. Most HDTVs are monitors -- meaning they have no HDTV tuners and require a video input. Satellite Satellite providers provide 4-5 network-like programming. HDNet, DiscoveryHD, ESPNHD, HDNetMovies, HBOHD, and ShowtimeHD are only available. Some satellite providers offer 1-2 pay per view channels in HD, and some provide CBS HD for rural areas without CBS (most markets have a black out on this feed). No local channels provided. The rest of the channels are 480p or 480i. You must also have a special HD receiver and HD subscription in order to receive content. One thing to note is the satellite provider "Voom". They have several (obscure, completely no name) networks that are unique to their system. If these channels interest you, it is worth taking a look. Currently, they provide the most channelage available on any TV distribution system. Keep in mind that most of it is no-name content on no-name channels (aka, filler content). So if you really want 24 hours of clay animation in 1080i on the claymation channel, or are interested in their 24 hour tennis HD channel, go right ahead. Cable Cable offerings are similar to satellite, but usually offer something called InHD, which is similar to HDNet. Some cable companies are either offering a couple local HD channels (not all). The rest of the channels are 480p or 480i. You must have an HD receiver and HD subscription in order to receive content. DVD This is a content delivery system too, even though it is not broadcast. Although some widescreen DVDs will look nice on your new TV, keep in mind it is all 703x480 content. Make sure you purchase discs with 1.85:1 ratios so it fills your screen, 2.35:1 will still be letterboxed slightly. You may also want to invest in a progressive scan player (they output 480p to 530p progressive signals). While a lot of movies are captured in progressive these days, some are not and will be interlaced on a progressive screen! High definition DVD does not yet exist. Video Game Consoles The only video game system that provides high definition output is the XBox. The rest are either 480p or 480i. Most XBox titles do not support 720p or 1080i unless specifically stated. The HDTV box checked usually means the title is available in widescreen, 480p. DVR's There are a couple of DVR products out there that support HD recording. Dish network offers the PVR921. HDTV Content Delivery systems aside, there is simply a lack of actual content. A lot is upconverted garbage and is the television equivlent of going into photoshop, taking 640x480 image from a 1/2 megapixel camera, scaling it to 1920x1080, and calling it a "2.0 megapixel image". The major networks (ABC, NBC, etc) and the HDTV cable/sat channels mentioned above are the only content providers of HDTV programming. While the specialized cable/sat channels broadcast HDTV (1080i) all day, Networks typically only kick in on HD during the evenings. As demand grows, more and more shows will be shot in HD -- or film transfered to HD. While HD shows sometimes display in letterbox (black bars) on an analog TV, we get something worse: most of our content has two black pillars on each side! A lot of advertisements and shows that are in "wide screen" actually are letterboxed and black barred. Perhaps pretend HDTV/widescreen content helps brand image?
Hype Definition Offenders Not to pick on anyone in particular, but here are some upscaling offenders: ESPNHD This is typically 703x480i 4:3 interlaced video upscaled to 1920x1080i and squashed to 16:9. It ends up being a bunch of blury fat people running around -- not even in the right aspect ratio. This channel is outright embarrassing...but ESPN is gearing up for HD and may provide some better content in the next year. FOX FOX claims to be in high definition. Its actually 480p in widescreen. CBS CBS has done a pretty good job at keeping us entertained with 1080i TV shows. During prime time, CBS plays special sequences during advertisements on their HD channel. "You are watching CBS in HDTV" is repeated over and over. The one in particular that is funny is the "CBS HD Sports", where all the sequences featured are actually 4:3 video upscaled (and squashed) to 16:9. I am sure CBS plans to offer sporting content soon, but this is pathetic. Video shot in HD but shown on channels that do not have any HD distribution A lot of channels (typically cable or satellite) that do not have any means to distribute high definition are airing wide-screen, letterboxed content. What is the point of this? The HD viewer has two choices at this point: Zoom in to the 640x480i video to fill the screen with blury video or enjoy the show/advertisement in black picture frame mode (or black horizontal and vertical bars). Local News Casts in HD We have one station in particular (KING 5, Seattle) that brags about its HDTV news broadcast. They forget to inform their viewers that they couldn't actually afford more than one HDTV camera in the newsroom (out of 3-4), so be prepared to switch resolutions a million times during the news broadcast. Local TV Shows in HD While Evening Magazine (King 5 local "HD" content) does occasionally air some sequences in 1080i, a majority of their episodes are upscaled 480i. What is worse is that conventional, analog TV users are forced to watch this show in black bar widescreen format. HDTV sounds awful, should I even bother? Consumers should realize that there is only little content available in HDTV. Buying that $5000 plasma screen will not improve the clarity and resolution of all your cable and satellite channels. Some people may choose to wait, but if you are in the market for a new TV, I would definately give the lower end models (<$2000 or <$1500) a very close look. It will still be a very long time before one can purchase an HDTV set for the price range of traditional televisions, so it may not be for everyone. HDTV is a double edged sword.....while a good 1920x1080 television program will take your breath away, you will puke once you are forced to watch something in 640x480 afterwards.
XBox in HD
Available Games The labeling on XBox games are becoming a little more standardized, but they are little help. Some say "HDTV", but you have to be careful with this one. Most that don't display a specific mode like 720p or 1080i are just merely a 480p (480 lines, progressive scan) in "wide screen". I bought Enter The Matrix, since it did advertise a mode of 1080i. It turns out, yes, it is in 1080i, but the textures were drawn for standard resolution. GTA 3 and Vice City are in "HDTV", but in reality, its just 640x480p in 16:9 (widescreen) mode. This keeps my TV from burning in, but does not really provide me with any display enhancement. Tue, 04 May 2004
A good listen
Mon, 03 May 2004
The Hype of "Mesh Networks"
I have to admit, the concept is pretty cool. I throw 30 "devices" in random Seattle locations, each discovering one another; creating relationships of some sort; and being able to transmit information (seamlessly, of course) from one end of the cloud to the other. If a few die, it would route round them. If there was a building in the way, it would find another path to send my information. And, last but very not least, this mesh network would provide such high QoS, I could send voice and video over it. And then we fall back to the real world -- none of this idealistic crap exists. Ouch, that hurt. Sure, there have been many attempts.....but no one has come to the table with a true, innovative, open solution. And no, configuring a bunch of radios to random IP addresses (just hoping we avoid guessing the same number) doesn't count. With the state of technology today, we may be asking for too much. First, we are burdened with half duplex radio technology, ie: 802.11. Strike 1. In order to have a true, dynamic mesh, we need omni directional antennas. Strike 2. Efficient distributed trust systems, resource allocation, QoS, and lack of spectrum to provide this. Strike 3. You're out! Its the omni-mesh paradox, and until we can somehow configure multiple full duplex pairs while talking to multiple hosts on the fly, I dont see our issues going away. MIT RoofNet (and a few other solutions popping up on the scene) might mitigate some of these hurdles. But if there was a widely available mesh routing solution, trust me, we'd be running it. I do have to say that some routing protocols, like AODV, are some nice attempts at mesh routing -- even though they have little to do with wireless in particular. I am not a big fan of stateful on-demand routing, but its a great concept, and has its place in the world. For past blog entries, check out the archive on the side or click here. |
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I bought a SprintPCS Vision Connection Card last week. This device uses
CDMA 2000, 1xRTT specifically. As documented earlier, I can squeeze quite
a bit out of this network.