Signal Strength and Distance

As always, your posts are spot on and very informative.

Thank you for your dedication to this site.

As my grandpappy always said, there is always someone who knows more.

Would that be enough for a hired content expert, probably not.
But if the information provided articulates the principle to the Judge or Jury, then it has been presented properly. I've found many times experts want to be accepted as experts so bad that they talk right over everyone's head. In addition, the first rule of testimony you are always taught is to keep it short and simple. Expounding on a topic opens you up to even more content questions about your testimony and could put you in a jam if you're asked more in detail questions about your testimony.

Lay witnesses are completely different from Judge to Judge, jurisdiction to jurisdiction, and State to State.

Greg,

If your avatar is a signal that you are doing this blindfolded to make it fair for the rest of us I must admit you have me outclassed by a long shot.

In the 1973 movie Magnum Force Clint Eastwood as Harry Callahan stated “A man’s gotta know his limitations.” This quote seems appropriate when commenting on RF and cellular signals in general.

Without a doubt the Sprint employee is smarter than I am, but it appears he overstated some things. I wonder what he would have said if he were asked what factors might cause a handset to hand off to a mast with a weaker signal? I’ve not read the full transcript, but I wonder if he ever mentioned line of sight, attenuation, down angle, beam width, signal strength, call volume or other factors?

To a properly trained investigator cellular records are a valuable tool, but they are no substitute for a thorough investigation.

I touched on this in another post, but in a sense we have created a climate in which we take a person from the law enforcement community and after a few days of training we turn them from a lay-person into an expert in cellular technology. We teach them to draw circles to estimate a person’s location and then turn them loose on the criminal justice system.

“This is an over simplification of what goes on, but I’m trying to make a point.”

I fully understand that we need to crawl “draw circles”, before we walk. But what does walking equal? What training is out there above the crawl stage and in the absence of funds to have “experts” take a second look at CDR’s what programs are in place to double check ones findings before the defense sends in a real expert to blow our findings out o the water?

Ed, twice now, this post and your last, you've mentioned peer reviewing or someone to consult with about findings or reports related to CDR analysis. I would be interested in discussing this with you if you think further discussion might be beneficial. I am prior LE and continue to do work in that field from a CDR Analyst standpoint. There is always something new to learn and share with others, that's why I'm on this site.
Give me a call if you want to discuss.

Greg's your insights and comments are worth their weight in gold.

Large bodies of water are the most amazing things when it comes to radio signals.

A cell tower 89km/59.3mi away, across the Great Lakes, would have a stronger signal than one at 1.6km/1mi away, through a metropolitan city. In this scenario, the picked and locked on tower was in Canada.

This was TDMA, and it was amazing how the carrier would have the gal to suggest that the user was in US for 5 minutes, then in Canada for 5, then back in the US again… Of course a short drive on the edge of this lake showed otherwise - A diesel VW Jetta is fast but not that fast . . . 2,136kph/1,416mph?

I guess not much has changed. mrgreen

Well, even with all of your caveats in mind, I do not think it is fair to be critical of Jeff in this case. In order to put forth this critical analysis of his testimony you must also have testified as an expert witness before. Right? In fact I am sure you have especially with all of that knowledge you have dripping out from everywhere. Then you must know the number two rule of giving testimony, yes? That would be to 'KISS IT', aka Keep It Simple Stupid, of course.

Were you my witness and had started spouting all of that tech-speak with all of the abbreviations we would have had a very long conversation. You would have lost the average jury in about two minutes and the average Judge in about three. It just would not work. Perhaps Jeff was coached to testify in that manner?

While distance is not the only factor, it is an evident factor, and perhaps one of the only factor the Jury could understand. I also doubt that the evidence that Jeff testified to was the only evidence in the trial.

Plus I detect a little subconscious lack of respect for the ‘back office staff’ such as Jeff; else you would not have even made the distinction. Just a guess but had Jeff been an engineer, like you, perhaps the tone you take would be different. We know nothing else of Jeff’s background or even why he was chosen to testify. We know nothing of the geographic terrain in which the cell tower was located. Was it the inner city where path loss would be a greater factor than if the tower were located in the Great Plains or perhaps the seacoast where the terrain may be just an extension of a continental shelf? Do we know the frequency of the cell phone transmissions or the tower transmissions? 800 MHz or 2.5 GHz or 5 GHz?

I seem to remember from my college physics and Ham Radio days that those things would make a difference in all of the factors you mention. I know for a fact that I can take my K2 portable rig with a maximum of 5 Watts RF to the Texas Coast, drape a G5RV dipole on the upper balcony of our condo, and make voice contacts with operators in Russia. If I am using Morse code, I can ‘talk’ to Japan and have done so several times.

Maybe we should have just left poor Jeff out of this all together and you could have just given us the solid information you put out there? But then engineers rarely made good writers, except of specifications.

Challenger,

I have nothing against Mr. Strohm, but is it fair to say that as a Custodian of Record I would think his presence at trial is to say that the records LE received are a true and correct copy of records kept by Sprint in their normal course of business.

I believe that if the DA or Defense starts asking questions outside of that it places the Custodian on rocky ground. If the DA felt in any way Strohm's testimony was "Lay-testimony" he/she should not have allowed him to answer the questions.

Maybe the Judge should have been a bit more careful in allowing it in the first place?

If you would look in to this case further they describe and define the legal definition of an "expert" for this trials purposes, and I quote………

U.S. v. Kale, supra.

As Wikipedia notes, an expert witness is a witness
who by virtue of education, training, skill, or experience, is believed to have expertise and specialized knowledge in a particular subject beyond that of the average person, sufficient that others may officially and legally rely upon the witness's specialized . . . opinion about an evidence or fact issue within the scope of his expertise, referred to as the expert opinion, as an assistance to the fact-finder.

In federal trials like this, the admissibility of expert testimony is governed by Rule 702 of the Federal Rules of Evidence, which states that if
scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.

The issue before the Court of Appeals, of course, was whether Strohm testified as an expert or as a lay witness, i.e., as a non-expert witness. In ruling on this issue, the Court of Appeals noted that under Rule 701 of the Federal Rules of Evidence, a lay witness may only offer opinions on subjects `not based on scientific, technical, or other specialized knowledge within the scope of Rule 702.’ [Rule 701© of the Federal Rules of Evidence.] In other words, a person may testify as a lay witness only if his opinions or inferences do not require any specialized knowledge and could be reached by any ordinary person.

U.S. v. Kale, supra.

The Court of Appeals held that the district court judge did not err in admitting Strohm’s testimony

We agree with the District Court that Strohm's limited discussion of the operation of cell phone towers did not require any `scientific, technical, or other specialized knowledge.’ [Rule 701 of the Federal Rules of Evidence.]

Strohm did not testify as to Kale's precise location when he called Buonanno; as the Government notes, such testimony would have required a technical background. Strohm's testimony, by contrast, consisted entirely of reading and interpreting Kale's cell phone records, including records detailing the locations of cell phone towers used to carry out his phone calls. A person of average intelligence would almost certainly understand that the strength of one's cell phone reception depends largely on one's proximity to a cell phone tower.

Even if this were not common knowledge, Strohm certainly had sufficient training and experience to testify about the operation of Sprint's cell phone towers. Strohm had worked for Sprint for over a year, was trained for four weeks on how to read cell phone records, and interacted regularly with radio frequency engineers.

Thus, he had sufficient `personal knowledge’ of how cell phone towers operate to testify reliably on this subject. [Donline v. Phillips Lighting N.Am. Corp., 581 F.3d 73 (3d Circuit 2009) (`When a lay witness has particularized knowledge by virtue of her experience, she may testify – even if the subject matter is specialized or technical – because the testimony is based upon a layperson's personal knowledge rather than on specialized knowledge within the scope of Rule 702’).

U.S. v. Kale, supra.

The Court of Appeals also found, as an alternative, that

even if the District Court's admission of Strohm's testimony had been erroneous, the error would be harmless. . . . The phone records presented at trial confirmed that Kale sent text messages and called Buonanno several times on the days of the Davis and Haussemann robberies. These contacts are consistent with Buonanno's testimony that Kale offered to sell him Percocet that he had stolen from the pharmacies on those days.

The problem there is that if there is no objection the question gets asked and even forced to answer.

You have to get your clients to understand the scope of things and that anything beyond that scope will cause things to get hairy.

The COR could have been been stipulated and saved a bunch of time. I can't remember a case in my career where it was needed to have a COR outside of their Affidavit, but I do know that the people who answer the phones and get the data to the requester, are no less important than any other area of the case.

Challenger,

I have nothing against Mr. Strohm, but is it fair to say that as a Custodian of Record I would think his presence at trial is to say that the records LE received are a true and correct copy of records kept by Sprint in their normal course of business.

I believe that if the DA or Defense starts asking questions outside of that it places the Custodian on rocky ground. If the DA felt in any way Strohm's testimony was "Lay-testimony" he/she should not have allowed him to answer the questions.

Maybe the Judge should have been a bit more careful in allowing it in the first place?