公开(公告)号：US20060098758A1

公开(公告)日：2006-05-11

申请号：US11214191

申请日：2005-08-29

申请人： Christian Luke ,  Ian Johnson ,  Mark Cope ,  Adrian Mansell ,  Steven Wood

发明人： Christian Luke ,  Ian Johnson ,  Mark Cope ,  Adrian Mansell ,  Steven Wood

IPC分类号： H04L25/49

CPC分类号： H04L27/3809

摘要： A system and method for controlling the gain in the forward signal path of a digital predistortion linearizer is disclosed. The loop gain of the predistortion system is driven to unity, where a separately controlled constant-gain observation path allows accurate gain control of the forward path. This is divided into digital gain from the predistortion function and analog gain from a Voltage Variable Attenuator (VVA) in the transmitter. The invention balances the distribution between these two domains in order to maximize dynamic range and minimize noise in the forward signal path. In order to distribute the forward path gain accurately, the characteristic of the VVA must be well known. Since these devices tend to be non-linear, with variable characteristic over temperature and batch, the invention compensates for this non-linear behavior by tracking the varying transfer characteristic of the VVA, giving a predictable local characteristic. Another aspect of the disclosed invention is the ability to operate with very low transmit power and loop gain levels, allowing accurate gain control during such scenarios as cell initialization, that require operation over a wide dynamic range.

公开(公告)号：US5706821A

公开(公告)日：1998-01-13

申请号：US366588

申请日：1994-12-30

申请人： Stephen John Matcher ,  Mark Cope ,  David Thomas Delpy

发明人： Stephen John Matcher ,  Mark Cope ,  David Thomas Delpy

IPC分类号： A61B5/00 ,  G01N21/49 ,  A61B6/00

CPC分类号： A61B5/14553 ,  G01N21/49 ,  A61B2562/0242

摘要： A spectrometric technique is described for quantitatively determining the change in concentration of a substance which is contained in a medium which both absorbs and scatters spectroscopically interrogated radiation, and in particular to the specific case in which the change in concentration of the substance occurs in one spatially distinct region of the medium. The medium includes a plurality of such regions displaying potentially different absorption and scattering properties to the radiation. Specific applications are disclosed involving the noninvasive determination of changes in concentration of the substances oxyhemoglobin and deoxyhemoglobin and/or changes in the redox state of the substance cytochrome oxidase within the brain or skeletal muscle, and in cases where the brain or skeletal muscle is interrogated by radiation in the near-infrared part of the electromagnetic spectrum through intervening surface tissues, i.e., cortical bone or adipose tissue, where it may be assumed that no changes of concentration of said substances occur within said surface tissues.

摘要翻译： 描述了一种光谱技术，用于定量测定吸收和散射光谱询问辐射的介质中所含物质的浓度变化，特别是在物质浓度变化发生在一个空间上的特定情况下 不同区域的介质。 介质包括多个这样的区域，其对辐射显示潜在的不同的吸收和散射特性。 公开的具体应用涉及无创测定氧合血红蛋白和脱氧血红蛋白的浓度变化和/或脑或骨骼肌内的物质细胞色素氧化酶的氧化还原状态的变化，以及在脑或骨骼肌受到询问的情况下 通过介入的表面组织即皮层骨或脂肪组织在电磁光谱的近红外部分中的辐射，其中可以认为在所述表面组织内不发生所述物质的浓度变化。