Otterbox Defender for Blackberry Curve

2008-10-10T18:09:00.007-04:00

After almost 3 years with Nextel and their rugged phones, I jumped ship and joined the Blackberry camp. This switch was mostly due to coverage issues, but there were some features available with a Blackberry that I didn't have with Nextel.

I own a small communications cabling company, and am frequently in environments where I would be concerned that the relatively delicate Blackberry might get damaged. While doing some research on available holsters, I came across the Otterbox Defender case. It sure looks rugged enough in the pictures on the manufacturer's web site - www.otterbox.com - and the available black/yellow color scheme fit right in as a replacement for my Nextel i580 with it's diamond plate panels. After using it for 3 months now, I can say that the Defender case offers all the protection I could expect - leaving only the trackball of the Blackberry Curve exposed.

For those of you not familiar with the Defender case, it consists of 3 layers of protection - a clear membrane that covers the front and back of the Curve (including the screen, keyboard and camera lens), a hard plastic layer that snaps on over the clear membrane, and a rubber layer that fits over the hard plastic layer.

Unfortunatley, the clear membrane covering the camera lens makes the camera all but useless. When I originally contacted Otterbox about this problem, their customer service representative indicated that he was unaware of any simlar reports. I later followed-up by submitting a trouble ticket on their web site, and received an acknowledgment of receipt, but no contact from them beyond that. Yesterday (7 weeks after submitting the trouble ticket) I called Otterbox to again try to get this problem fixed. Though they say that some others have also reported the problem, they offered no solution other than to cut a hole in the membrane, which would void the warranty. And when I asked for a replacement membrane as a possible solution, they refused.

I am posting this to alert others to the problem BEFORE they make a purchase. So if you're considering an Otterbox Defender case for your device, keep this in mind.

Below is a composite picture - the left side taken with the thoroughly-cleaned membrane in place, the center taken with the membrane removed, and the right side take with the membrane from a Defender case for the Pearl covering the lens. All original pictures were taken at a resolution of 1600 x 1200, cropped to a size of 360 x 480, and merged together. No other editing was done. You be the judge.

Choosing a Qualification Tester

2008-03-07T18:37:00.016-05:00

Introduction
I recently found myself in the market for a qualification tester - a relatively new category of cable tester that emerged in 2005 with the announcement of the Validator, manufactured by Test-Um (now owned by JDSU). Other entries in the market now include Ideal Industries' SignalTek, Byte Brothers' Real World Certifier, and Fluke Networks' CableIQ. With this many choices in a category that's not very well defined, and not endorsed by any cabling manufacturers, I had a lot of work to do before I could come to a purchase decision that I would be satisfied with. So I set out to gather as much information as I could about each of these units, and qualification testing in general.

Certification, Qualification and Verification - what's the difference?
Basically, certification tests a cable for compliance with TIA cabling standards specified for a category of cable (i.e. Category 5, 5e, 6, etc.) Qualification tests a cable for compliance with IEEE standards for a protocol (typically 10BaseT, 100BaseT or Gigabit ethernet). Verification tests a cable for proper wiring according to TIA standards (i.e. T568A or T568B, and sometimes USOC). Ideal Industries, JDSU, and Fluke Networks all claim that their products use the IEEE 802.3 standard as a basis for their tests. IEEE 802.3 clause 40.7.2 states that:

The transmission parameters contained in this subclause are specified to ensure that a Class D link segment of up to at least 100 m will provide a reliable medium. The transmission parameters of the link segment include insertion loss, delay parameters, characteristic impedance, NEXT loss, ELFEXT loss, and return loss.

Link segment testing shall be conducted using source and load impedances of 100 Ω. The tolerance on the poles of the test filter used in this subclause shall be no worse than 1%.

Fluke Networks has a more detailed explanation in this article.

Comparing Units
I did as detailed a comparison as possible considering that I didn't have any of these units on-hand. I reviewed almost all of the sales information on the manufacturers' web sites, product manuals, knowledgebase articles, demo videos... well, you get the idea. All of these units do basic wiremap testing - identifying opens and shorts as well as miswires - but not all of them detect split pairs.

Signaltek
According to the Signaltek manual:

SIGNALTEK uses the IEEE 802.3ab (Gigabit Ethernet) standard as a reference for cable performance testing. Rather than a traditional certification test where frequency-based parameters such as Near End Crosstalk (NEXT) and return loss are measured, performance or qualification testing, as it is sometimes called, is a Bit Error Rate Test (BERT). Data packets are sent down the cable to the remote handset then re-transmitted back to the display handset where the number of lost or errored packets is counted. The results are displayed for the user to get an instant view of the cable’s performance. A cable performance test is marked as a “pass” or “fail” based on the IEEE 802.3ab parameters which specify the number of error packets allowed in a given test time.

IEEE 802.3 has specific requirements for link transmission parameters. But the above-quoted section of the manual says that qualification tests don't measure any of these parameters. A Bit Error Rate (BER) of 10^-10 is a stated objective of the IEEE 802.3 link transmission parameter requirements - it is not a requirement in and of itself.

In addition to the Cable Performance BER test, Signaltek can perform several other BER tests with varying packet sizes, attempting to simulate VoIP traffic, web traffic and IP video traffic. Although these additional tests sounded redundant to me at first, I found this article from Hubbell indicating that packet size can have an effect on the error rate on a marginally-compliant link.

Signaltek also performs a wiremap test measuring length (via TDR), identifying opens and shorts, and also measures delay skew (a parameter required for gigabit ethernet). Diagnostic features appear to be equivalent to those of a decent verification tester - detecting an open or short, and providing a distance to the fault (distance to short requires TDR). The manual contains no references to split pairs (which can lead to excessive crosstalk), crosstalk, attenuation (insertion loss), return loss or propagation delay, except to say that it doesn't measure them and that crosstalk and attenuation may contribute to Cable Performance failures. The Signaltek gives no indication as to whether any of these are the cause of an individual test failure. A telltale sign of Signaltek's lack of troubleshooting features appears in the manual under the heading of Performance Test Failures:

The first step in troubleshooting a performance test failure is to check the quality of the termination at the work station and patch panel. Installation guidelines allow for no more than ½” of untwist in each pair and no more than 1” of jacket to be removed at each termination. Excessive untwisting can lead to high Near End Crosstalk (NEXT) within the cable and an unacceptable ACR.

They're actually telling you to physically check the cable. Don't get me wrong - a physical inspection is never a bad idea. However, they're telling you to do this because aside from locating opens and/or shorts (which are already ruled out prior to conducting the BER test) they have no diagnostic capabilities whatsoever.

Signaltek appears to be concerned with the end result (can the link handle gigabit traffic within the error rate anticipated in IEEE 802.3) rather than the factors that contribute to it (acceptable levels of crosstalk, attenuation, propagation delay, return loss, etc). When the end result is satisfactory you're probably not going to ask any questions. But when it's not, and you do ask questions, it's not going to have any answers.

Signaltek includes some nice usability features such as predefined cable types, the ability to organize cables tests by job (i.e. site, building, etc), ability to copy results to a USB memory stick, print directly to supported USB printers, and the use of an XML report format - meaning results can be viewed and printed with any web browser.

Autotest Time: 10 seconds (minimum, depending on optional tests)

Additionally, Signaltek includes some LAN testing features that I won't get into here.

Pros:

Uses readily available AA batteries (no proprietary batteries that, when discharged, leave to stuck)
No PC software to install - results can be transferred directly to USB memory stick or to PC (tester appears as a USB mass storage device)
BER test evaluates cable under simulated in-use conditions
Can perform extended BER tests for up to 24 hours to identify intermittent problems
Models available with fiber qualification capabilities
Internal storage accommodates up to 20,000 tests

Cons:

Doesn't measure any link transmission parameters
No troubleshooting ability for failed tests
Inexpensive additional remotes are not available
Provides a single test port (all non-8P8C connectors require an adapter)
Reports appear unprofessional (sample)- no page break control, color report prints poorly in black & white, and most of it doesn't even print in color on a color printer
Reports not easily customized - operator and site info can be entered in tester, but no company logo can be added, nor can the report be easily edited on the PC
Report format allows results to be tampered with too easily (I know this sounds contradictory, but it's too hard to edit what should be easily edited, and too easy to edit what you shouldn't be able to edit at all)

Validator
As with Signaltek, Validator uses a BER test as its primary criteria. However, Validator also measures propagation delay, NEXT, attenuation, return loss, SKEW (I think they're referring to delay skew) and Signal-to-Noise Ratio (SNR) (all of which can be disabled), and tests for split pairs. There is no mention of ELFEXT, a required link transmission parameter, in any Validator literature.

Validator is the only unit to provide a full compliment of test ports including 8P8C, 6P6C, coax ("F"), and banana jacks (for two-wire testing). All others require the use of adapaters or expect you to plug 6P6C plugs into the 8P8C jacks on your tester - subjecting them to abuse and leading to potential performance/repair issues.

Though some of the manufacturer's literature claims that Validator uses TDR for measuring length and distance to fault, the manual states that both TDR and capacitance methods are used. While there is no mention in the manual to specifying an NVP value (a necessary component of TDR calculations), it does describe where to set capacitance values for built-in or custom cable types. This leads me to believe that TDR is not actually used by Validator.

For each defined cable type you can specify a length limit. Length limits are part of the TIA specifications for various categories of cables. IEEE specifications (which the manual claims Validator uses as a reference) on the other hand, specify propagation delay limits of 1000ns for 10Base-T and 570ns for both 100Base-T and 1000Base-T. Allowable length will actually vary based on the NVP value for your cable. Since Validator provides no way to specify an NVP, you can't be sure what your allowable length is. FYI - using an average NVP value of 0.72 (assuming plenum-rated cable), the corresponding allowable cable lengths are 215m (708ft) for 10Base-T, and 123m (403ft) for 100Base-T and 1000Base-T.

Validator will test phone cables using 1, 2, or 3-pair USOC wiring scheme.

Downloading test results from Validator requires navigating through your folders using Windows Explorer, and performing a copy (or cut) and paste operation.

Autotest Time: not specified

Fluke Networks has this article comparing Validator and CableIQ.

Additional features include flashing hub/switch lights, tone generator. An alternate model, Validator NT, also includes LAN testing features similar to those on the Signaltek.

Pros:

Included Compact Flash card (32MB) accommodates up to 6,000 tests
Ability to create a list of cables to be tested in the included Plan-Um software, and upload it to the tester, saving time during testing

Cons:

Inexpensive additional remotes only provide wiremap capabilities (i.e. no testing of speed or performance parameters)
Uses proprietary rechargeable batteries (leaving you stuck if they're discharged)

Real World Certifier
Real World Certifier appears to perform something similar to a BER test, but they don't call it that. To perform this "Level 2" test (as they call it), you'll need a network switch (preferably gigabit, not included) on one end of the cable. Attenuation is also measured in the Level 2 test. Their "Level 1" test detects opens, shorts, miswires and split pairs (and distance to fault), and measures length, NEXT, NEXT(FAR) (don't ask me what that is), propagation delay and skew (delay skew), and provides a projected speed capability. Level 1 tests can be performed using the included remote (no switch required). There is no mention of return loss, a required link transmission parameter, in any of the information I could find on Real World Certifier.

The Level 1 test also includes something they call "cable typing" - determining whether a cable is Cat3, Cat5, Cat5e or Cat6.

To download reports to a PC for printing you'll need Microsoft Excel and a PC with a serial port. Their "software" is an Excel spreadsheet with a macro that imports the data into Excel for viewing and/or printing.

Fluke Networks has this article comparing Real World Certifier with CableIQ.

Autotest Time: 90 seconds + (according to the above-referenced article)

I was unable to find a user manual online.

Pros:

Price - about 50-70% the price of the other testers listed (not including the switch required for Level 2 testing.

Cons:

Reporting requires Microsoft Excel, with possibly lowered security settings.
Reporting requires serial port - easily remedied with a USB-to-serial adapter, but an odd interface choice nonetheless.
Level 2 testing requires AC power (for switch), which may not be readily available on new construction or renovation sites
Doesn't seem to offer any ability to test voice cables

CableIQ
CableIQ detects opens, shorts, miswires and split pairs (and distance to fault), and measures crosstalk, attenuation, return loss, delay skew (gigabit only) and ELFEXT (gigabit only) - providing a distance to fault for crosstalk and return loss issues. It does not perform a BER test. As mentioned earlier, a Bit Error Rate of 10^-10 is an objective of the IEEE 802.3 specifications for gigabit ethernet, not a requirement of the specifications. (Meeting the requirements naturally produces the result - the result itself is not a requirement). This article in the Fluke Networks knowledgebase mentions this as well.

Autotest Time: 6 seconds

Pros:

Only tester listed that tests all link transmission parameters specified by IEEE 802.3
Can detect bridge taps in voice cabling
Though not cheap (about $75 each), six additional identifiable remotes are available and are functionally identical to the included remote, allowing you to perform seven complete tests before returning to the panel
Professional appearance of report (sample)
Uses readily available AA batteries

Cons:

No pre-defined or user-definable cable types (though NVP values are separately specified for twisted-pair and coax cables)

Which One Did I Choose?
I eliminated Signaltek from my short list because of it's BER-only testing and the quality/appearance of the reports it generates.

Real World Certifier lost me with its lack or return loss measurement, the requirement to separately purchase a switch for complete testing, the requirement of AC power for the switch, and their entire approach to reporting.

This left me with Validator and CableIQ. Validator lost this contest for several reasons:

No ELFEXT measurement
Price - Validator is $240 more than the base CableIQ model (CIQ-100)
Multiple Remotes - Validator's multiple remotes are for wiremap only; CableIQ's multiple remotes are fully functional
The Fluke Networks name carries with it a comfort level that Test-Um just doesn't have (this is only my opinion)

I ended up buying a CableIQ Advanced IT Kit (CIQ-KIT, adding six more remotes, an Intellitone probe, and a hard carrying case to the base model) from www.datacomtools.com.

During my own tests on a renovation project, where work area outlets are easily accessible, I found the storage capacity for 250 tests could be limiting on larger jobs. At the rate I was testing I could have performed 250 tests in about 4 hours.

Metro Connect

Otterbox Defender for Blackberry Curve

Choosing a Qualification Tester