Here's the abridged, 1:30 AM version...
- The product you listed hits the price point by utilizing off-the-shelf 1000BaseT circuitry to run a Bit Error Rate Test (BERT) at the 1000Mbps rate. This does not mean that the cable is frequency swept to 1Ghz. This is a very similar scheme to the Fluke CableIQ qualifier, and the JDSU Validator. (note that neither of them say "certifier", and that the product listed is a "real world certifier")
- 1000BaseT crams all the bits on the wire by modulating the signal. The data is coded using a scheme called five level pulse amplitude modulation or PAM-5.
- The bandpass frequency of a channel is determined by a combination of the Nyquist Theorem and the Shannon Law. The Limitation determined by signal bandwidth is expressed as R=2Wlog2M, where R is the rate of data transmission, W is the maximum frequency and M is the number of levels of encoding
- Plugging in the formula for the specs for 1000BaseT Ethernet...
This is a four level encoding so M=4 (5th Level is for synchronization only)
Therefore the bandwidth (W) = R / log24 * 2 which gives 62.5MHz (R = 250Mbits/s)
- Old school two-cat extenders do little more than pre-equalize for expected cable losses over a specified cable type. This is the reason for the limited distances, skew equalization circuitry, fuss over which cable pairs are used, length rotary switches, shielded cable, et cetera. They aren't coding the data at all. They require a MUCH higher bandpass bandwidth, on the order of what Brent has explained already - 829Mbps per channel for 1080i, per channel. In this scenario, you would want a certification tester that would sweep test the cable itself for full passband bandwidth.
- HDBaseT utilizes a coding scheme very similar (trade secret squirrel sauce) to PAM-5 to send the bits down the wire. 62.5Mhz per pair, for 1080p / 24 / 8 bit color is what was verbally stated by an engineer-in-the-know. Nobody can tell for sure, because the chip vendor won't publish specs and nobody I know has access to the test equipment needed to confirm. I'd still personally want a sweep test of the cable, but the product listed by the OP will *probably* do just fine for guaranteeing 720p/1080i. 1080p is a lot of bandwidth. You definitely want to sweep test with a proper tester.
- Breaking the bank is 100% relative. I've got a Fluke DTX-1800, which is one of only a handful of testers which actually, truly, literally sweep test the cable up to the bandwidth rated by the device, 500MHz. My kit, including SM and MM fiber optics kits was around $10k. For $500, and a warm-fuzzy feeling, this product is worth the money, given that you understand the limitations and don't come back to the board claiming that "I CERTIFIED THE CABLE1!@", because you really didn't...
Light reading:
example fluke dtx certification report:
[Link: taiko-net.com.tr]Ethernet coding:
[Link: dell.com][Link: cisco.com][Link: myaccount.flukenetworks.com]